Anycode

* Rename module `anycode.generate` as `anycode.generation`
* Add `anycode.clear`, `anycode.dump`, `anycode.dumps`

* Fix the typing of generated functions to specify the `_openai_*` attributes
* Support functions generated by ChatGPT under a name that doesn't match the one defined by the user
* Don’t expose `anycode.this`

* Use our own OpenAI API client rather than the [module-level one][mlo]
* Set `anycode.__version__`

[mlo]: https://github.com/openai/openai-python?tab=readme-ov-file#module-level-client

Initial release.