Better handle the dirty state of Airmap's flightplan

The "Now" button now sets a "now" flag instead of adjusting the start time. Once the flight is created, the actual "now" time is set for flight start time.
The button is also exclusive. Once set, the start time slider is hidden as it becomes irrelevant.

If briefing evaluation returns no authorization, assume none is required. This is reflected in the UI as "Authorization Not Required".

Add control to set flight duration (which ultimately sets the end_time of flight)

Handle flight start/end time
Handle start/stop traffic monitor
Only start telemetry if enabled
Added a "Now" button for the flight start time
Collect advisories only when the rules change

More clang warnings cleanup

Change feature default values to something that will be identified as "not set". When a flight is created, features with missing values (not set) are not included. Note that all these are persistent, which may create a problem if something changes (different vehicle with large weight difference for instance). As the subsequent use of these are persistent, a question may not be asked because it's already set (the brief only asks for missing or problem values).

Remove delete flights and add "End" active flight instead
Work on flight geometry (flight list)

Implementing authorization management

Flight management with date range, delete flights.

Cleaning up old vehicle manager and getting it ready to actually provide services for a vehicle (flight management)
Added submit flight plan
Added update flight plan
Disable flight features as these don't seem to be quite working (values must be initialized and validated before submission as backend doesn't validate and the objects don't initialize their members)

Permit refactoring
QGCButton tweaks

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

Collect rulesets from briefing

Add flight plan deletion

Moved flight planning away from "Flight Management" to its own class. Planning does not need a connected vehicle.