fix(radio): enforce rules for custom switches when setting up in the UI.

[philmoz]

Fixes #4990

Changes to the UI for setting up custom function switches to prevent invalid setup.

[3djc]

Overall very nice (i realize this is WIP)

• I think we can hide Groups that have no switches in them
• There is a functional issue, where selecting a switch for the group doesn't delete the '=' for other switch in group
• I think most, if not all, of the functions in model_setup should move to a common place, like switches.cpp

I will wait for that change to be merged to address #4989, since both need similar functions added

[philmoz]

• I think we can hide Groups that have no switches in them

Done.

• There is a functional issue, where selecting a switch for the group doesn't delete the '=' for other switch in group

I think this is fixed now.

• I think most, if not all, of the functions in model_setup should move to a common place, like switches.cpp

Moved the ones that aren't UI specific.

I've also renamed FS_START_UP to FS_START_ON and FS_START_DOWN to FS_START_OFF to avoid confusion and because the previous names were backwards. E.G. if you use one of the custom switches in a SF then the ON state shows as SW DOWN, not UP which is consistent with usage for normal switches.

[3djc]

Perfect !

[philmoz]

For completeness, I've added an option to set the startup state of a group to 'Off'.
This will force the group to be all off on startup.
Only applies to groups that are not set to always on.

[3djc]

Successfully tested on T20V2

[philmoz]

Changed the diag page to use arrows and OFF/ON labels.

[elecpower]

Add space character between Group and number ie Group1 -> Group 1 for labels and drop down lists

Would it not be more appropriate for the 'Start Switch' label to be 'Start' as the option per group is not always a switch eg Restore or Off