feat(nv14/el18): Add help popup showing mapping when using hats as keys.

[philmoz]

For when I forget what the key assignments are :)

[rotorman]

I wonder if graphical representation might be more intuitive for the user. Due to portrait display, showing the trims in two rows is less perfect though. Here two images I created for further discussion:

Left trim hat:

Right trim hat:

[pfeerick]

I have no preference either way, but appreciate the reminder as to what the heck the stick mapping actually is 🤣 . The caveat with doing it as an image is it can't be translated, so instead you would need to use the image of the hats and overlay text on it. Showing the hats one after the other is perfectly fine since there is a Left and Right heading.

[richardclli]

Another radio that may use HAT mode is PL18 series, need to consider this as well.

[rotorman]

In order to be able to also use this feature on radios that do not have hat type trims (e.g. PL18/Paladin EV), a suggestion to use "trim-navigation" instead of "hats mode" to keep it more generic.

[pfeerick]

Just gonna leave this as it is for now, to be tweaked in 2.11 if needed/desired.