Try to set --python-executable to a local python from the local venv

[kaste]

If we use a globally installed mypy, we could still point it to a local venv by setting --python-executable automatically.

SublimeLinter's layering is not ideal here, as we ant to set an argument after cmd has run. We could add it to run but then we have to mangle the complete and finished cmd (list[str]). There is also no clear extension point when a globally executable is searched for. So we would need to interfere that from the finished cmd as well. (IIRC)

Generally, there is a chicken-egg problem, where get_working_dir() is computed after cmd has been resolved. But we already want to access it in cmd(). Look like get_working_dir is a function from (context, canonical_name_of_the_linter) -> Optional[str] (but not right now) and the canonical name of the linter (e.g. mypy, ruff etc.) is nowhere stored explicitly. However, self.name typically is the name we're looking for, just implicitly.