Have different modes for the Airspace Widget (Plan/Fly)

Create a "Dead Mouse Area" control to eat mouse events underneath desired area. This is to prevent mouse events from leaking through controls underneath the area.
Replace original "NoMouseThroughRectangle" as this is more versatile.
Prevent mouse through events from leaking underneath the Fly View tool strip.

Adding missing qgcView to QGCMapPolygonVisuals instance in SurveyMapVisual.qml

Make all argument to AirMap queries based on what the screen shows (bounding rectangle and/or radius), respecting the limits imposed by AirMap.

AirspaceManager is now exposed by QGroundControlQmlGlobal instead of Vehicle (available all the time)

Plus various bug fixes from flight testing

Also remove custom gimbal support

Fix sorting issues with QmlObjectListModel
Show airspaces in Plan View as well

Added an "unavailable" icon for when no vehicle is connected
Toggle restriction overlays (map) on/off based on the airspace widget being expanded/collapsed respectively

Handled "airspace visible" state (not done)
Adjusted restriction map items color and opacity
Added/Updated icons for airspace traffic
Adjust colors for text over maps

All settings wired and persistent
Cleanup non Airmap builds

Eliminated flight widget "states"
Define flight widget top margin (plugin options)

Adjust colors
Remove unused image

Number calc doesn't work so hiding for now

Fix #5812
Show an error message when creating a KML without 2 items at least
Signed-off-by: Patrick José Pereira <patrickelectric@gmail.com>