docs: add missing modules to sphinx documentation build (#5017)

* docs: add missing modules to sphinx documentation build

Add RST files and toctree entries for modules that were not included
in the sphinx doc build:

API:
- opentelemetry._events (Events API)
- opentelemetry.attributes (Attributes utilities)
- opentelemetry.trace.propagation (Trace context propagation)

SDK:
- opentelemetry.sdk._events (Events SDK implementation)
- opentelemetry.sdk._logs.export (Log export processors and exporters)

Closes #2573

Signed-off-by: Raajhesh Kannaa Chidambaram <495042+raajheshkannaa@users.noreply.github.com>

* fix: add Event class to nitpick_ignore for sphinx docs build

Signed-off-by: Raajhesh Kannaa Chidambaram <495042+raajheshkannaa@users.noreply.github.com>

* fix: add changelog entry and nitpick_ignore for get_finished_logs

Add CHANGELOG entry for the docs PR and suppress the Sphinx
cross-reference warning for get_finished_logs (referenced as :func:
in a docstring we did not modify).

* fix: add Token class to nitpick_ignore for sphinx docs build

* address review: remove events API, fix get_finished_logs xref, move changelog

- Remove docs/api/_events.rst and docs/sdk/_events.rst (events API is
  deprecated per MikeGoldsmith, avoid exposing it in docs).
- Remove _events entries from api/index.rst and sdk/index.rst toctrees.
- Drop Event class nitpick_ignore entry (no longer needed).
- Fix docstring cross-reference on InMemoryLogRecordExporter from :func:
  to :meth: since get_finished_logs is a method, and drop its
  nitpick_ignore entry.
- Move changelog entry from 1.41.0/0.62b0 to Unreleased.

* docs: remove trace.propagation.rst per maintainer review

Submodule .rst files were removed in #5133. This was missed during the
prior merge.

Reviewed-by: Leighton Chen

* docs: re-export AnyValue from attributes module for sphinx forward-ref resolution

sphinx_autodoc_typehints calls get_type_hints on BoundedAttributes,
which uses _ExtendedAttributes (Mapping[str, 'AnyValue']) from util.types.
The forward ref to 'AnyValue' resolves in BoundedAttributes' __globals__
(the attributes module), not in util.types where it is defined.
Re-export AnyValue into the attributes module namespace so the
forward ref resolves and the docs build succeeds.

Signed-off-by: Raajhesh Kannaa Chidambaram <495042+raajheshkannaa@users.noreply.github.com>

* docs: use explicit re-export for AnyValue (fix ruff)

Signed-off-by: Raajhesh Kannaa Chidambaram <495042+raajheshkannaa@users.noreply.github.com>

* docs: use __all__ for AnyValue re-export to satisfy both pylint and ruff

* docs: inject AnyValue into attributes namespace via conf.py instead of re-exporting

Signed-off-by: Raajhesh Kannaa Chidambaram <495042+raajheshkannaa@users.noreply.github.com>

* docs: migrate changelog entry to towncrier fragment

Address @emdneto's feedback: replace direct CHANGELOG.md edit with a
.changelog/5017.fixed fragment per the new towncrier workflow added in

* docs: drop dead trace toctree (no trace.{status,span,propagation}.rst exist)

The Submodules toctree referenced files that were never added in this PR and trace.propagation.rst was removed earlier per review. Sphinx -W treats the missing toctree target as a warning-as-error, breaking the docs build.

Signed-off-by: Raajhesh Kannaa Chidambaram <495042+raajheshkannaa@users.noreply.github.com>

---------

Signed-off-by: Raajhesh Kannaa Chidambaram <495042+raajheshkannaa@users.noreply.github.com>
Co-authored-by: Raajhesh Kannaa Chidambaram <495042+raajheshkannaa@users.noreply.github.com>
Co-authored-by: Leighton Chen <lechen@microsoft.com>
Co-authored-by: Emídio Neto <9735060+emdneto@users.noreply.github.com>