Update global theme and modernize code
The following change were applied:
- Move away from KPackage and KDeclarative (this is ihmo not needed and loading the qml files with qrc is simpler)
- Remove code handling for Qt < 5.14 (IIRC we need depends now on Qt 5.15)
- Improve QML and make it responsive
- Rename everything from the look and feel to global theme (I will notify the localization team when this get merged)
Edited by Carl Schwan