PYTHON-2442: Refactor: use _asdict() in _options_dict()

[RinCodeForge927]

This PR implements the TODOs mentioned in PYTHON-2442 by replacing manual dictionary construction in _options_dict() with calls to _asdict() in both CodecOptions and JSONOptions. This is more idiomatic as these classes inherit from NamedTuple (or use its interface).

[blink1073]

Hi @RinCodeForge927, thank you for the fix! Looking at the original commit, I think we can remove the private method _options_dict entirely. I verified we don't use it in motor.

[RinCodeForge927]

Thanks for the suggestion! I've removed _options_dict entirely and updated with_options to use _asdict directly. Please take a look.

[blink1073]

Looks like at least one more usage needs to be updated based on the docs build failure:

      File "/home/docs/checkouts/readthedocs.org/user_builds/pymongo/envs/2670/lib/python3.11/site-packages/bson/codec_options.py", line 486, in with_options
        opts = self._options_dict()
               ^^^^^^^^^^^^^^^^^^
    AttributeError: 'CodecOptions' object has no attribute '_options_dict'

[RinCodeForge927]

I've cleaned up the remaining references to _options_dict in codec_options.py and confirmed that all tests pass locally. The method is now completely removed. Thank you!

[blink1073]

LGTM, thank you!

[RinCodeForge927]

Thank you for the review! I'm very happy to contribute a small improvement to such a great project. Glad I could help!