Mypy-protobuf

- Remove 3.7 compatibility for typing_extensions.final/Literal
- Bump protobuf to 4.25.3

- Add gRPC aio stub and servicer generation (489)
- Bump tested dependencies to pyright==1.1.319, mypy==1.4.1, protobuf==4.23.4, grpcio-tools==1.56.2
- Drop support for py 3.7. Add support for py 3.11.
- Don't add unnecessary flake8 noqa F821 comments. (Become compatible with flake8-pyi>=23.5.0.)

- Mark messages as typing.final
- Switch to use the reserved mypy-protobuf extension option numbers https://github.com/protocolbuffers/protobuf/blob/main/docs/options.md
- Bump protobuf dependency to 4.21.8
- Skip unnecessary flake8 noqa F821 on module scope fwd reference classes

- Prefer (mypy_protobuf.options).casttype to (mypy_protobuf.casttype)
- Allows us to use a single extension number
- Applies to casttype,keytype,valuetype
- Deprecate (but still support) the old-style extension
- Prefer importing from `typing` over `typing_extensions` on new enough python versions
- Support emitting module docstrings
- Make generated code flake8 compatible
- Convert extensions.proto to proto3
- Drop support for Python 3.6 [EOL]
- Bump to grpc-stubs 1.24.7
- Require protobuf 3.19.4
- Bump support to mypy 0.941
- Use PEP 604 Union syntax `X | None` rather than `Optional[X]`
- Moved from dropbox/mypy-protobuf to nipunn1313/mypy-protobuf
- Nipunn is the primary maintainer and plans to continue maintenance!

- Remove unnecessary `...` in generated files.
- Reorder/reference enum classes to avoid forward references.
- Support `*_FIELD_NUMBER` for extensions
- Bump types-protobuf dependency to 3.19
- Require protobuf 3.19.3
- Support DESCRIPTOR: ServiceDescriptor in py generic services
- More accurately represent method names in py generic services (done -> callback, self -> inst)
- More accurately represent method names in grpc services (`request` -> `request_iterator`)
- Internal: Get tests to pass on pure-python protobuf impl (minor semantic differences)
- Internal: Bump pyright in testing to 1.1.206
- Internal: Use stubtest to validate generated stubs match generated runtime

- Require protobuf 3.19.1
- Change `EnumTypeWrapper.V` to `EnumTypeWrapper.ValueType` per https://github.com/protocolbuffers/protobuf/pull/8182.
Will allow for unquoted annotations starting with protobuf 3.20.0. `.V` will continue to work for the foreseeable
future for backward compatibility.
- suppress pyright warning reportSelfClsParameterName when a proto field is named `self`
- Allow optional constructor keywords for primitive field types in proto3, following this [chart](https://github.com/protocolbuffers/protobuf/blob/master/docs/field_presence.md#presence-in-proto3-apis).
- Reorder Enum helper classes to eliminate pycharm errors