The korean keyboard wraps InputText and overrides some
of its methods to process input in some specific way.
When switching to another keyboard layout, the original
methods need to be restored.
* Switch the last few remaining icons to true glyphs
(Del/Backspace & Enter).
Also, allow a glyph to be rendered in (fake) bold, and use it for Enter.
* Update fonts
Pickup the tweaked nerdfonts for the backspace symbol
Follow-up to #5583.
* Add separate Cyrillic/Russian keyboard
* And remove that from English
* Update French keyboard (is easy)
* Remove yahzhert, that was just a double of QWERTY
* Update Spanish keyboard
* Reduce Japanese to 4 layers and add globe
* Reduce Korean to 4 layers
* Reduce Greek to 8 layers
