Keymap: Move navigation buttons closer to the middle on XD75:skewwhiffy (#4118)

Keymap: Move navigation buttons closer to the middle on XD75:skewwhiffy (#4118)

* RGB toggle button

* Remove custom lighting effects

* Fix small bug in Symbols layer

* Ignore mod tap interrupt in XD75 for skewwhiffy, and split layers into two for more flexibility and fix persistent layer issue

* Replace shift in nav layer with IntelliJ omnibox shortcut to avoid a sticky shift

* Remove custom setting in config, because it were annoying, it were.

* Move navigation buttons in one key

* Some review markups

* Use enums for layers

* Use LAYOUT_ortho_5x15

* Revert some capitalization changes made by accident