modules: commander: Group arm requirements in just one byte and add a new requirement

Instead of having several bools to each requirement to arm, lets group then
in a byte and use bitmask.
This also add a new arm requirement "arm authorization" that
will be implemented in another patch.

src/modules/commander/commander_tests/state_machine_helper_test.cpp

@@ -297,8 +297,7 @@ bool StateMachineHelperTest::armingStateTransitionTest()
 				nullptr /* no mavlink_log_pub */,
 				&status_flags,
 				5.0f, /* avionics rail voltage */
-				check_gps,
-				false, /* valid mission not required*/
+				(check_gps ? ARM_REQ_GPS_BIT : 0),
 				2e6 /* 2 seconds after boot, everything should be checked */
 				);