Chat2func

- fix bug on enum default value
- fix responses exporting

- Small bugfix on annotation warning
- Separate individual `function_call` from dict choice of `function_calls`

- Add defaults to schema args
- Optionally adds response schema on return types
- Better wraps classes
- Changes `.json` property to `.__schema__` on `json_schema` wrapped objects.

Adds support and improvements for:
- nested types and ForwardRef's
- all pydantic types
- unifying project install extras
- `json_schema` for methods, staticmethods, classmethods
- adds pydantic type support for `json_schema` decorated classes
- jsonschema for function calling validation
- better firebase server exporting
- lots of improved tests!

Drops support for:
- python 3.7

- clean up firebase server exports
- improve readme readability