[MNT] Drop black, add ruff up rules, improve private vs public imports and add general purpose entry-point to the GUI

[mscheltienne]

The main changes are:

• Drop black in favor of ruff
• Enable the ruff up rules
• Add missing imports in the __init__.py that would prevent some:

import mne_icalabel

mne_icalabel.xxx.yyy

• Add arguments to the command-line entry point of the GUI to pass raw/epochs and ICA files for the GUI.
• Add workflow and script to generate stubs automatically along the codebase, for better type-hints in VSCode.