Fixing the telemetry RSSI indicator.

Instead of hardcoded "QGroundContorl" strings

This makes VehicleComponents reusable from core plugin without
requiring override of prerequisiteSetup

No more user prompting

Convert bool settings to SettingsFact

Use component id from heartbeat

Prevent shutdown ordering crashes

Forcing QGC to use Mavlink V2 if vehicle supports it.

No signing support yet

_finalize methods need information which is not available if all you
have is a mavlink_message_t

This mechanism automatically queues data into the correct thread where necessary, otherwise the method is invoked directly with low overhead.

At the same time remove the UDP socket event workaround. It is not a problem.

- Pervasive change to automatically connect to known board types
- Lots of additional changes along with this:
- More exposure of objects/properties to Qml
- Much restructuring in LinkManager and LinkManager clients

- Pervasive change to automatically connect to known board types
- Lots of additional changes along with this:
- More exposure of objects/properties to Qml
- Much restructuring in LinkManager and LinkManager clients

- Pervasive change to automatically connect to known board types
- Lots of additional changes along with this:
- More exposure of objects/properties to Qml
- Much restructuring in LinkManager and LinkManager clients