HEARTBEAT and commander failsafe handling cleanup

msg/telemetry_status.msg

msg/vehicle_status.msg

src/modules/commander/Commander.cpp

src/modules/commander/Commander.hpp

src/modules/commander/commander_params.c

src/modules/commander/state_machine_helper.cpp

src/modules/commander/state_machine_helper.h

src/modules/mavlink/mavlink_main.cpp

src/modules/mavlink/mavlink_receiver.cpp

src/modules/navigator/navigator_params.c