Add synchronous stubs

[AdrienVannson]

Adapted from danielgtaylor/python-betterproto#647

[leonardgerardatomicmachinescom]

Would be even nicer now that you made grpclib optional.
Before I spend a bit of time getting my MR on top of your code, can you give me (everyone) a timeline for when you will have a release, and what are the plans for supporting the code.
We would like to switch to a better betterproto, and your fork might be that, but we need some confidence before switching.

[AdrienVannson]

Sorry, I missed your comment. Yes, I plan to make grpclib optional. I think I will merge this in a few days.

Thank you for your interest! I think it will take me a few months before the first stable release (I hope it will be less, but it will depend on how the development goes). I want to avoid breaking changes after this release, so I'd like to make sure everything is fine before doing so. After that, yes, I plan to keep maintaining the library.

[Copilot]

Pull Request Overview

This PR adds synchronous stub support by introducing a new client generation option throughout the codebase. Key changes include updating the protoc command options in tests, adding a ClientGeneration enum with new properties in the settings, and updating the plugin parser to handle the new client_generation option.

Reviewed Changes

Copilot reviewed 6 out of 11 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
tests/util.py	Inserts new command-line options for client_generation in protoc invocation.
tests/inputs/simple_service/simple_service.proto	Adds a basic proto file for testing the new client generation functionality.
src/betterproto2_compiler/settings.py	Introduces a ClientGeneration enum and adds a client_generation field to the Settings dataclass.
src/betterproto2_compiler/plugin/parser.py	Updates get_settings to parse client_generation options and return a Settings instance accordingly.
pyproject.toml	Updates dependency definitions to include grpc-async extras and adds the strenum dependency.

Files not reviewed (5)

• src/betterproto2_compiler/templates/header.py.j2: Language not supported
• src/betterproto2_compiler/templates/service_stub.py.j2: Language not supported
• src/betterproto2_compiler/templates/service_stub_async.py.j2: Language not supported
• src/betterproto2_compiler/templates/service_stub_sync.py.j2: Language not supported
• src/betterproto2_compiler/templates/template.py.j2: Language not supported