Instead us a Toolbox concept which hangs off of QGCApplication

- select active vehicle
- arm/disarm
- select flight mode

- MultiVehicleManager is a Qml friendly replacement for UASManager
- Vehicle is a replacement for both UAS and AutoPilotPlugin

If Facts are referenced from FactPanelController, we need to reference
count the AutoPilotPlugin such that it doesn’t get destroyed until
after the FactPanelController is destroyed.

QGCUASParamManager and friends are replaced by FactSystem

More consistent with Qml usage pattern

Passing parameters QVariantMap across C++ boundary was causing crashes
in Qt due to Qml array bugs. Referencing same Fact* across Qml boundary
in multiple QQuickWidgets caused jScript GC to crash.

Also, uas is kept in object

- properties now hand off of main “autopilot” object in qml
- Added support for summary items through qml

Used for unit testing