Copter: setting ESC param to 2 skips high throttle check

This allows the all-at-once ESC calibration to be performed on a setup
in which the RC input takes some time to come online.
Plane: add support for DO_SET_ROI within mission
Rover: add support for DO_SET_ROI within mission
Rover: add support for DO_SET_ROI outside of missions
Plane: add support for DO_SET_ROI outside of missions