* Introduce FileData Filtering for Kiosk and Kid Modes to:
1. In Kiosk mode: Hide items with metadata tag `<hidden>true</hidden>`
2. In Kid mode: only show items with metadata tag `<kidgame>true</kidgame>`
* ES will auto-revert UI mode back to Full when there is nothing at all to show.
* Changing the setting hideQuitMenuOnKidUI to true will hide this menu.
- Refactoring System Environment data
- Added Virtual System Manager class
- Added "all", "favorites" and "last played" systems
- Added GuiInfoPopup class for notifications
- Added Favorites to metadata, as well as a shortcut to toggle favorites
- Added warning if enabling systems but themes don't support it
- Added "filter by favorites" per system
- Adjusted "Go to Random Game" behavior to account for the fact that we now have an "All Games" system
- Added "sort by system name" for the collections
