pyrepl: restructure imports to give a meaningful error when curses is missing on POSIX

# Bug report

### Bug description:

If CPython is built and deployed onto a POSIX system without curses,  we get an error about importing msvcrt which is a Windows library and thus confusing

```
# python3
random: python3: uninitialized urandom read (24 bytes read)
Python 3.13.2 (main, Feb 12 2025, 13:57:13) [GCC 13.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
warning: can't use pyrepl: No module named 'msvcrt'
```


Here's the import log
```
# trying /usr/lib/python3.13/_pyrepl/__main__.cpython-313-arm-linux-gnueabi.so
# trying /usr/lib/python3.13/_pyrepl/__main__.abi3.so
# trying /usr/lib/python3.13/_pyrepl/__main__.so
# trying /usr/lib/python3.13/_pyrepl/__main__.py
# trying /usr/lib/python3.13/_pyrepl/__main__.pyc
# code object from '/usr/lib/python3.13/_pyrepl/__main__.pyc'
# trying /usr/lib/python3.13/_pyrepl/main.cpython-313-arm-linux-gnueabi.so
# trying /usr/lib/python3.13/_pyrepl/main.abi3.so
# trying /usr/lib/python3.13/_pyrepl/main.so
# trying /usr/lib/python3.13/_pyrepl/main.py
# trying /usr/lib/python3.13/_pyrepl/main.pyc
# code object from '/usr/lib/python3.13/_pyrepl/main.pyc'
# trying /usr/lib/python3.13/_pyrepl/simple_interact.cpython-313-arm-linux-gnueabi.so
# trying /usr/lib/python3.13/_pyrepl/simple_interact.abi3.so
# trying /usr/lib/python3.13/_pyrepl/simple_interact.so
# trying /usr/lib/python3.13/_pyrepl/simple_interact.py
# trying /usr/lib/python3.13/_pyrepl/simple_interact.pyc
# code object from '/usr/lib/python3.13/_pyrepl/simple_interact.pyc'
# trying /usr/lib/python3.13/_pyrepl/readline.cpython-313-arm-linux-gnueabi.so
# trying /usr/lib/python3.13/_pyrepl/readline.abi3.so
# trying /usr/lib/python3.13/_pyrepl/readline.so
# trying /usr/lib/python3.13/_pyrepl/readline.py
# trying /usr/lib/python3.13/_pyrepl/readline.pyc
# code object from '/usr/lib/python3.13/_pyrepl/readline.pyc'
# trying /usr/lib/python3.13/_pyrepl/unix_console.cpython-313-arm-linux-gnueabi.so
# trying /usr/lib/python3.13/_pyrepl/unix_console.abi3.so
# trying /usr/lib/python3.13/_pyrepl/unix_console.so
# trying /usr/lib/python3.13/_pyrepl/unix_console.py
# trying /usr/lib/python3.13/_pyrepl/unix_console.pyc
# code object from '/usr/lib/python3.13/_pyrepl/unix_console.pyc'
# trying /usr/lib/python3.13/_pyrepl/curses.cpython-313-arm-linux-gnueabi.so
# trying /usr/lib/python3.13/_pyrepl/curses.abi3.so
# trying /usr/lib/python3.13/_pyrepl/curses.so
# trying /usr/lib/python3.13/_pyrepl/curses.py
# trying /usr/lib/python3.13/_pyrepl/curses.pyc
# code object from '/usr/lib/python3.13/_pyrepl/curses.pyc'
# trying /root/_curses.cpython-313-arm-linux-gnueabi.so
# trying /root/_curses.abi3.so
# trying /root/_curses.so
# trying /root/_curses.py
# trying /root/_curses.pyc
# trying /usr/lib/python3.13/_curses.cpython-313-arm-linux-gnueabi.so
# trying /usr/lib/python3.13/_curses.abi3.so
# trying /usr/lib/python3.13/_curses.so
# trying /usr/lib/python3.13/_curses.py
# trying /usr/lib/python3.13/_curses.pyc
# trying /usr/lib/python3.13/lib-dynload/_curses.cpython-313-arm-linux-gnueabi.so
# trying /usr/lib/python3.13/lib-dynload/_curses.abi3.so
# trying /usr/lib/python3.13/lib-dynload/_curses.so
# trying /usr/lib/python3.13/lib-dynload/_curses.py
# trying /usr/lib/python3.13/lib-dynload/_curses.pyc
# trying /usr/lib/python3.13/site-packages/_curses.cpython-313-arm-linux-gnueabi.so
# trying /usr/lib/python3.13/site-packages/_curses.abi3.so
# trying /usr/lib/python3.13/site-packages/_curses.so
# trying /usr/lib/python3.13/site-packages/_curses.py
# trying /usr/lib/python3.13/site-packages/_curses.pyc
# trying /root/curses.cpython-313-arm-linux-gnueabi.so
# trying /root/curses.abi3.so
# trying /root/curses.so
# trying /root/curses.py
# trying /root/curses.pyc
# trying /usr/lib/python3.13/curses.cpython-313-arm-linux-gnueabi.so
# trying /usr/lib/python3.13/curses.abi3.so
# trying /usr/lib/python3.13/curses.so
# trying /usr/lib/python3.13/curses.py
# trying /usr/lib/python3.13/curses.pyc
# trying /usr/lib/python3.13/lib-dynload/curses.cpython-313-arm-linux-gnueabi.so
# trying /usr/lib/python3.13/lib-dynload/curses.abi3.so
# trying /usr/lib/python3.13/lib-dynload/curses.so
# trying /usr/lib/python3.13/lib-dynload/curses.py
# trying /usr/lib/python3.13/lib-dynload/curses.pyc
# trying /usr/lib/python3.13/site-packages/curses.cpython-313-arm-linux-gnueabi.so
# trying /usr/lib/python3.13/site-packages/curses.abi3.so
# trying /usr/lib/python3.13/site-packages/curses.so
# trying /usr/lib/python3.13/site-packages/curses.py
# trying /usr/lib/python3.13/site-packages/curses.pyc
# trying /usr/lib/python3.13/_pyrepl/_minimal_curses.cpython-313-arm-linux-gnueabi.so
# trying /usr/lib/python3.13/_pyrepl/_minimal_curses.abi3.so
# trying /usr/lib/python3.13/_pyrepl/_minimal_curses.so
# trying /usr/lib/python3.13/_pyrepl/_minimal_curses.py
# trying /usr/lib/python3.13/_pyrepl/_minimal_curses.pyc
# code object from '/usr/lib/python3.13/_pyrepl/_minimal_curses.pyc'
# destroy _pyrepl._minimal_curses
# trying /usr/lib/python3.13/_pyrepl/windows_console.cpython-313-arm-linux-gnueabi.so
# trying /usr/lib/python3.13/_pyrepl/windows_console.abi3.so
# trying /usr/lib/python3.13/_pyrepl/windows_console.so
# trying /usr/lib/python3.13/_pyrepl/windows_console.py
# trying /usr/lib/python3.13/_pyrepl/windows_console.pyc
# code object from '/usr/lib/python3.13/_pyrepl/windows_console.pyc'
# trying /root/msvcrt.cpython-313-arm-linux-gnueabi.so
# trying /root/msvcrt.abi3.so
# trying /root/msvcrt.so
# trying /root/msvcrt.py
# trying /root/msvcrt.pyc
```

The import checks are structured like so in _pyrepl/readline.py

```python
try:
    from .unix_console import UnixConsole as Console, _error
except ImportError:
    from .windows_console import WindowsConsole as Console, _error
```

Maybe this should be:

```python
if sys.platform == "win32":
    from .windows_console import WindowsConsole as Console, _error
else:
    from .unix_console import UnixConsole as Console, _error
```

It's not clear to me if cygwin is expected to work with the windows console or the unix console.

The `register_readline` handler already has similar branching logic:

```python
                if os.name == "nt":
                    import _pyrepl.windows_console
                    console_errors = (_pyrepl.windows_console._error,)
                else:
                    import _pyrepl.unix_console
                    console_errors = _pyrepl.unix_console._error
```


The restructured import should allow the correct import error to bubble up and set `CAN_USE_PYREPL=False`.

```
# python3 -c "import _pyrepl.curses"
  File "<string>", line 1, in <module>
    import _pyrepl.curses
  File "<frozen importlib._bootstrap>", line 1360, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1331, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 935, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 1026, in exec_module
  File "<frozen importlib._bootstrap>", line 488, in _call_with_frames_removed
  File "/usr/lib/python3.13/_pyrepl/curses.py", line 28, in <module>
    from . import _minimal_curses as _curses  # type: ignore[no-redef]
  File "<frozen importlib._bootstrap>", line 1415, in _handle_fromlist
  File "<frozen importlib._bootstrap>", line 488, in _call_with_frames_removed
  File "<frozen importlib._bootstrap>", line 1360, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1331, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 935, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 1026, in exec_module
  File "<frozen importlib._bootstrap>", line 488, in _call_with_frames_removed
  File "/usr/lib/python3.13/_pyrepl/_minimal_curses.py", line 32, in <module>
    _clibpath = _find_clib()
  File "/usr/lib/python3.13/_pyrepl/_minimal_curses.py", line 28, in _find_clib
    traceback.print_stack()
Traceback (most recent call last):
  File "/usr/lib/python3.13/_pyrepl/curses.py", line 23, in <module>
    import _curses
ModuleNotFoundError: No module named '_curses'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/python3.13/_pyrepl/curses.py", line 26, in <module>
    import curses as _curses  # type: ignore[no-redef]
    ^^^^^^^^^^^^^^^^^^^^^^^^
ModuleNotFoundError: No module named 'curses'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "<string>", line 1, in <module>
    import _pyrepl.curses
  File "/usr/lib/python3.13/_pyrepl/curses.py", line 28, in <module>
    from . import _minimal_curses as _curses  # type: ignore[no-redef]
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
ImportError: cannot import name '_minimal_curses' from '_pyrepl' (/usr/lib/python3.13/_pyrepl/__init__.py)
```

The `ModuleNotFoundError("curses library not found", name="_pyrepl._minimal_curses")` is getting morphed into that `ImportError` above by `from . import X`. 

```python
def _find_clib() -> str:
    trylibs = ["ncursesw", "ncurses", "curses"]

    for lib in trylibs:
        path = ctypes.util.find_library(lib)
        if path:
            return path
    raise ModuleNotFoundError("curses library not found", name="_pyrepl._minimal_curses")
```

Dropping the name property seems to resolve that but maybe there's a better solution.

### CPython versions tested on:

3.13

### Operating systems tested on:

Linux

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pyrepl: restructure imports to give a meaningful error when curses is missing on POSIX #130046

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Uh oh!

pyrepl: restructure imports to give a meaningful error when curses is missing on POSIX #130046

Description

Bug report

Bug description:

CPython versions tested on:

Operating systems tested on:

Metadata

Metadata

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