Feature Request: Add Channels Setup Page to Config/Tuning tab

#### Issue details
Request: Editing all CHx_OPT in a compact drop down list.

My thought is that on the Config/tuning page of Mission Planner, there could be a "Aux Channels Setup" page (or similar name) where ALL channels (CH6-14) can be configured via a drop down menu. Maybe it could even be integrated into the flight modes setup screen? It would be even better if the particular channel's drop down cell highlighted when the associated CH on the transmitter is flipped high. Personally, I have to frequently flip between the param list (CHx_OPT) and the Radio calibration page to identify which of my channels are mapped to which switches. Instead of the operator having to associate particular switches with channel numbers, this would allow associating particular switches with particular functions in ardupilot.

I have described this in more detail and even mocked up some tentative/prototype mission planner screens here (please forgive the repeating save trim/auto options, i used MS Paint to mock this up):

https://discuss.ardupilot.org/t/request-editing-all-chx-opt-in-a-compact-drop-down-list/42637

#### Version
This is just a feature request

#### Platform
[ X ] All
[ ] AntennaTracker
[ ] Copter
[ ] Plane
[ ] Rover
[ ] Sub

#### Airframe type
All. This feature pertains to any operator who wants/needs to use aux channels.

#### Hardware type
NA - this request relates to ardupilot firmware setup, not a particular set of hardware

#### Logs
NA. Just a feature request.

Start by reviewing the Config/Tuning tab and the existing flight modes and radio calibration screens in Mission Planner, then read the linked discussion and mockup. The requested result is an Aux Channels Setup page for CH6-14 with compact drop-down editing, transmitter-state highlighting, and a clear mapping between switches and ArduPilot functions.

Written by the indexing model from the issue text.