Consolidate settings

QGCExternalLibs.pri

src/Airmap/AirMap.SettingsGroup.json

src/Airmap/AirMapSettings.cc

src/Airmap/AirMapSettings.h

src/Airmap/AirmapSettings.qml

src/Airmap/QGroundControl.Airmap.qmldir

src/FlightDisplay/FlightDisplayViewWidgets.qml

src/PlanView/PlanView.qml

src/Settings/App.SettingsGroup.json

src/Settings/AppSettings.cc

src/Settings/AppSettings.h

src/api/QGCCorePlugin.cc

src/ui/preferences/GeneralSettings.qml