keyboards/ryanskidmore: add rskeys100 keyboard (#15506)
* keyboards/ryanskidmore/rskeys100: add rskeys100 draft firmware
* keyboards/ryanskidmore/rskeys100: fix firmware
* ryanskidmore/rskeys100: fix remaining bugs
* keyboards/ryanskidmore/rskeys100: finishing touches on firmware
* keyboards/ryanskidmore/rskeys100: migrate from full replacement matrix scanning to lite, move rgb matrix enable call to keymap
* keyboards/ryanskidmore/rskeys100: remove undefines, clarify comments
* ryanskidmore/rskeys100: remove unused imports
* keyboards/ryanskidmore/rskeys100: pr feedback
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