…5492)

Blocks: DataDog/documentation#17518

The ddtrace Opentelemetry `TracerProvider` is an internal component. It
is configured when `ddtrace-run` is used to start an application. This
PR add the `TracerProvider` to the public API so that it can be
configured by applications that do not use `ddtrace-run`.

### Summary of Changes
 - Renames the `ddtrace._opentelemetry` package to `ddtrace.otel`
 - Renames opentelemetry `span.py` to `_span.py`
 - Renames opentelemetry `trace.py` to `_trace.py`
 - Updates imports to use the package and module names

## Checklist

- [x] Change(s) are motivated and described in the PR description.
- [x] Testing strategy is described if automated tests are not included
in the PR.
- [x] Risk is outlined (performance impact, potential for breakage,
maintainability, etc).
- [x] Change is maintainable (easy to change, telemetry, documentation).
- [x] [Library release note
guidelines](https://ddtrace.readthedocs.io/en/stable/contributing.html#Release-Note-Guidelines)
are followed.
- [x] Documentation is included (in-code, generated user docs, [public
corp docs](https://github.com/DataDog/documentation/)).
- [x] PR description includes explicit acknowledgement/acceptance of the
performance implications of this PR as reported in the benchmarks PR
comment.

## Reviewer Checklist

- [ ] Title is accurate.
- [ ] No unnecessary changes are introduced.
- [ ] Description motivates each change.
- [ ] Avoids breaking
[API](https://ddtrace.readthedocs.io/en/stable/versioning.html#interfaces)
changes unless absolutely necessary.
- [ ] Testing strategy adequately addresses listed risk(s).
- [ ] Change is maintainable (easy to change, telemetry, documentation).
- [ ] Release note makes sense to a user of the library.
- [ ] Reviewer has explicitly acknowledged and discussed the performance
implications of this PR as reported in the benchmarks PR comment.