kcms: Replace the old joystick KCM
Problems:
- This KCM is ancient, it's barely maintained.
- Still QtWidgets, and not really for any good reason.
- No one wants to touch this thing
🤣
This is based on QtQuick and Kirigami, and features a much cleaner and modern codebase. It's functionally equivalent to the old KCM, save for a tracing and calibration feature. It's designed to be a drop-in replacement and a base for future improvements and features.
Internally, the KCM name is updated to "kcm_gamecontroller" in many places where "kcm_joystick" was used.
Note: This is intended to be a drop-in replacement for the old KCM, and some of the features in the original repository (https://invent.kde.org/redstrate/gamepad-kcm) are not present. I still hope to get some in before 6.x, but this is at least make it ready for 6.0 if we miss the freeze.