Add gui option for osd_stick_overlay_radio_mode

[RobertoD91]

Is your feature request related to a problem? Please describe

It would be helpful to have a option in the OSD section for selecting osd_stick_overlay_radio_mode

Describe the solution you'd like

A simple drop-down menu in OSD tab

Describe alternatives you've considered

A reminder in the help section osdDescElementStickOverlayLeftand osdDescElementStickOverlayLeft

Other information

No response

[haslinghuis]

This would require an additional OSD element variant in firmware.

[nerdCopter]

i think he just wants the option in GUI

# get osd_stick_overlay_radio_mode
osd_stick_overlay_radio_mode = 2
Allowed range: 1 - 4

i.e. new MSP read/write.

[haslinghuis]

Alternative: parameter overlayRadioMode is already in MSP.
Just can't decide where we should place it as it's only used for stick overlay element[s].
A variant would create a selection on the element.