Rewriting proto scripts in Python #12511

I've hinted at it previously, I am now officially suggesting we rewrite the shell scripts found in scripts in Python instead.

• They only worked* on Linux (now MacOS)
  • Attempting to make them work on MacOS, @sobolevn accidentally broke the sed command in macos does not have sed --in-place argument #12330
  • since the difference is in quote, I don't see a clean way to reconcile the commands by, for example, storing the command in a variable.
• We require additional tools to be installed that are not in our dev requirements (wget on mac, unzip on ubuntu, wsl on Windows)
• We could speed up the runs by using UV as we could assume deps in requirements-tests.txt have been installed (if we even decide to still create a different venv, rather than consolidating mypy-protobuf versions)
• It's extremely slow on Windows WSL2 because it just has very slow disk operations across the VM boundary ([wsl2] filesystem performance is much slower than wsl1 in /mnt microsoft/WSL#4197 (comment) & https://learn.microsoft.com/en-us/windows/wsl/compare-versions#comparing-features)
• Our existing tooling could do some basic checks on the scripts.

I am opening this issue to share my intention, but I doubt there'd be much opposition ^^" If anyone would like to take this, let me know, otherwise I'll probably do it sometimes within the next week.