Add support for plasma bigscreen using mediacenter fileselectors
Plasma Bigscreen based on Plasma Nano Shell (the same used in plasma mobile) is a containment for TV Screens aimed at running on Single Board Computers, with the goal of the whole User Interface being accessible by only a remote control with arrow keys, this requires implementing arrow key navigation across the whole UI. To keep the ui experience separated between what one would expect on the phone, desktop vs a TV screen that is to be used via key navigation we use Qt File Selectors that can help target loading specific QML UI files based on the set environment variable.
This PR Adds the following:
- QML UI specifically targeted for Key Navigation under the +mediacenter file selector
- Removing resource alias to make it compatible with Qt File Selectors
Testing on any development environment:
- export QT_FILE_SELECTORS=mediacenter