Protogen

* 5bb14dc docs: document extensions (14)
* 25eec8b build: run "poetry lock"
* 4bb70c3 build: set homepage
* 4147520 Ensure imports are sorted (11)
* 3a350a6 Lossen requirement on protobuf package
* 6f28550 Enable IDEs to find type annotations

* 53d3a31 docs: restructure and add more samples
* d491877 test: switch to use the protogen.test method
* 035691f test: switch to pytest
* 0198bf8 feat: add protogen.test module
* 4e754dd feat: relative type name resolution
* d56ce09 feat: Allow CodeGeneratorResponse.supported_features to be set
* 57aa38f fix!: full py_ident.py_name for nested messages
* f36958e chore: update poetry install in github actions
* 7dee38f docs: describe --<plugin>_out flag
* b4c9d13 docs: fix empty sample
* cf9e62f docs: add badges and links to README

Changes

* 1492b68 refactor: py_import_func to return PyImportPath
* bb1d541 feat: expose Registry on Plugin
* 63d657b fix: unexpected kwarg in ResolutionError
* 44f8164 docs: update protogen module docstring
* 5dffad6 chore: remove empty grpc_gateway module

Initial release version of the open source package.