Plane: move rudder-arming arm checks into Plane's AP_Arming

[peterbarker]

No description provided.

Requested changed were made

[peterbarker]

The follow-on PR for this is here: #16091

It moves the now-factored code in Plane's RC_Channel up into the parent class and uses it across the other relevant vehicles.

[Hwurzburg]

@peterbarker @tridge tested in SITL....it behaves like current for rudder arm/disarm....however, current is broken for rudder disarming if in QRTL, QLAND, or QACRO....you cant disarm once armed on the ground unless you change to a mode that can disarm or issue the MAVLINK disarm command....since QRTL and QLAND should autodisarm, it may not be a big problem, but QACRO is I think....
and while testing I also found that if you are on the ground, disarmed, and switch to QAUTOTUNE it rejects the mode change (which I think is correct) BUT sends a MAVLINK message that the mode change WAS accepted..it can be switched into from another mode on the ground if already armed.....once in QAUTOTUNE and on the ground you can arm and disarm with rudder. So the mode accepted message needs to be corrected I believe

[peterbarker]

On Tue, 22 Dec 2020, Henry Wurzburg wrote: @peterbarker @tridge tested in SITL....it behaves like current for rudder arm/disarm....however, current is broken for rudder disarming if in QRTL, QLAND, or QACRO....you cant disarm once armed on the ground unless you change to a mode that can disarm or issue the MAVLINK disarm command....since QRTL and QLAND should autodisarm, it may not be a big problem, but QACRO is I think.... and while testing I also found that if you are on the ground, disarmed, and switch to QAUTOTUNE it rejects the mode change (which I think is correct) BUT sends a MAVLINK message that the mode change WAS accepted..it can be switched into from another mode on the ground if already armed.....once in QAUTOTUNE and on the ground you can arm and disarm with rudder. So the mode accepted message needs to be corrected I believe

@Hwurzburg so can we merge this and change behaviour in another PR? Or two, by the sounds of it. There were obvious cleanups to be done which I resisted (eliminating the static list of modes that allow arm/disarm for a callback on the current flightmode, for example).

[Hwurzburg]

Yes,works just like current....

[peterbarker]

Thanks @Hwurzburg