Allow developers (or advanced users) to override gstreamer debug settings

Checklist enforcing

Remove unused function

Fix Done in Toolbar when switching to Plan View

Allow developers (or advanced users) to override UI settings - quite useful if you set your debug settings in QtCreator and do not depends on QGC settings state (they are reset to default sometimes, for example)

Code documentation and updates

Tweak output.

Exclude QObject and Item. Everything on the c++ side derives from QObject and most things on the QML side derives from Item.

Every single line of this function is commented out, and the
documentation of GStreamer says that it's uneeded.

Various fixes

CP - If GCS starts receiving its own coordinates, don't change the map center if it is already tracking the vehicle.

VideoPageWidget: Enable camera control if using gstreamer