positionroam: BrakeRate parameter drives rate of deceleration

1. plan_setup_braking calculates distance and time to halt from decel rate and a few assumptions
2. Sanity check for multirotoar initially
3. Pathplanner accurate dT calculation and variable timer as calculated in plan_setup_braking
4. Added brakeRate parameter to flightmodesettings
5. Moved braketimeout period to flightstatus as a calculate value.
altituderoam: Add state transition to altitudeholdstatus for debugging