[Keymap] Add preonic/kjwon15 layout (#6812)

[Keymap] Add preonic/kjwon15 layout (#6812)

* Add my custom keymap

* Remove del key on left, Add pscr

* Move Audio MOD key to pass ctrl

* Change startup song

* Enable clicky sound

* Swap alt and gui

* Fix semitones

* Add mouse layer

* Change startup song

Additionally, fixup 5 halftones

* Add ctrl key to ctrl+click

* Move media keys to restore raise number keys

* Move mouse key layer switch

* Swap media keys as normal

* Fix music map

* Move mouse speed limit to correct position

* Move prtscr

* Align keycodes

* Add ctrl/esc, swap smart space keys

* Change colemak, dvorak into custom layout

* Fix pure mode (left space)

* Fix mouse mode interrupt

* Add Middle mouse click

* Add Lefthand mouse scroll

* Temporarily disable mouse speed

* Rename custom layout to kjwon15

* Change readme

* Apply suggestions from code review

Co-Authored-By: fauxpark <fauxpark@gmail.com>
* Apply suggestions from code review

* Apply suggestions from code review

Co-Authored-By: fauxpark <fauxpark@gmail.com>
* Update from default keymap's function