Add Python code checks using pytype, mypy, pyright and pylint

[bernhardkaindl]

Hello @freddy77!

As written before, this PR only adds new files for code checks, so it should not cause conflicts.

I successfully tested mypy and pyright in GitHub CI!

Here is a sample (private) PR that shows an intentional CI failure that generated an automated code review comment for the intentionally added broken code:

xenserver-next#1
xenserver-next#1 (comment)

Besides the comments from mypy and pyright (Microsoft's code checker) that I tested on this PR,
I also integrated the pylint and pytype checkers.

All checkers also work locally with minimal effort by using pre-commit.
It is a battle-hardened CI solution that installs Python environments for
each CI check and runs the checks in their respective environment.

Howto:

• Installation:
  • Ubuntu 24.04 and similar: sudo apt install pipx;pipx install pre-commit
  • Older distributions: pip install pre-commit (if your system allows it)
• Full initial run (including Python environment creation+installation): pre-commit run -av
• Incremental runs the current state of the local work tree: pre-commit run.