[Keyboard] Add Runner3680 with 5x6+5x8 layout (#14617)
* [Keyboard] Add Runner3680 keyboard with 5x6 + 5x8 layout
* [Keymap] Use general audio key codes instead of MacOS specific ones
* [Keymap] Add via support
* [Keyboard] Add config for RGB Matrix feature for runner3680 5x6+5x8 layout
* Add license to .c and .h files
* Remove unused code
* [Keymap] Rename 'JIS' directory to be lower cased
* [Keyboard] Explicitly define enabled RGB lighting effects for Runner3680
* [Keyboard] Remove unused code of Runner3680
* [Keyboard] Move RGB Matrix related config to keyboard's rules.mk file
* [Keymap] Clean up default keymaps of Runner3680
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