Invert mypy file checking and add pre-commit hook

[svartkanin]

trafficstars

Some changes to how mypy is applied:

• We're now excluding files to be checked by mypy instead of including them explicitly, which means that all new files will have to be compliant

Add an OPTIONAL pre-commit hook configuration file, this run some checks before actually committing which should indicate if github actions are going to fail :) The hooks can easily be installed with

pip install pre-commit
pre-commit install

[svartkanin]

Extracted the mypy configuration from the github action into it's own mypy.ini configuration so it can be called easily from github and the pre-commit hook

[svartkanin]

@Torxed If you're okay with this one could we merge it in? Otherwise it will inevitably cause a lot of conflicts whenever something else gets merged :)

[svartkanin]

Has been merged into https://github.com/archlinux/archinstall/pull/1604 and will be added with it