feat(ios): Add option for keyboards menu to show language (+keyboard)

When in the Keyman app (Android and iOS) pressing the Globe (K_LOPT) button shows a list of languages (+ smaller keyboard names) which is great. But in other apps Keyman's system keyboard only shows the keyboard name, which is unhelpful if you use the same keyboard for many languages, as with Naija Type.

Suggested spec:
- Automatically when building the menu, if a keyboard has > 1 language assigned, display the language & keyboard name in the keyboard menu: Language - Keyboard.
- - eg Ishɛ - Naija Type
- - Nyankpa - Naija Type
- AND/OR: Add an option 'System Keyboard menu display' like the 'Spacebar Caption' option, to choose whether to show 'Language' or 'Keyboard' or 'Both' in the menu. Or, an 'Automatic' option as above.

Obviously it would be best if a feature could be added that Keyboard App Builder can also use.