[Keyboard] Add Crossed Keys/Keyhive Nightmare (#6796)
* initial draft of nightmare files
* fixed pins
* fixed MT keycodes
* updated READMEs
* updated title in main readme
* updated for split space
* added OPT_TAB
* fixed layer 1 keymap
* Add DEL to keymap
* Update Bootmagic pins
* Update Keymap
* Fix missing )
* Update Up arrow on keymap
* Add hosted image for Nightmare render
* Update info.json for Nightmare layout
* Resolve suggestions from drashna
* Add split space layout in nightmare.h and info.json
2a948e7771
