When the input to Generator.integers was 2**32, the value 2**32-1
was being passed as the `rng` argument to the 32-bit Lemire method,
but that method requires `rng` be strictly less then 2**32-1.

The fix was to handle 2**32-1 by calling next_uint32 directly.
This also works for the legacy code without changing the stream
of random integers from `randint`.

Closes numpygh-16066.

Assert that an invalid value (2**n-1 for n = 8, 16, 32, 64) has not
been passed to the Lemire function.

Add repeatability tests for when the range of the integers is `2**32`
(and `2**32 +/- 1` for good measure) with broadcasting.  The underlying
functions called by Generator.integers and random.randint when the
inputs are broadcast are different than when the inputs are scalars.