Also merged MissionController and MissionEditorController into single
MissionController implementation

Mostly accomplished by delay loading Qml elements

For QWidget we will just use the Qt default font sizes. This removes
the extra QQuickWidget creation which breaks boot Qml Profiling

This is in preparation for full Qml main window

- Follow Vehicle
- Center map on vehicle

- Only show video option if supported
- Persist settings
- Show/Hide/Add items correctly

- Restructured a number of MissionItem properties as well