Keymap: Adjusted keymaps for standardisation (#3874)

Keymap: Adjusted keymaps for standardisation (#3874)

* Added HHKB with 7U space bar
There are backlight changers on the function Z, X and C, mediat controls
have been removed.

* Fixed the default layout and added a keymap
GUI and ALT keys were swapped.
My own keymap which adds calculator, removes power, removes eject.

* Adjusted naming convention of hhkb layout layer

Fixed as per required from code review.

* Updated for qmk configurator

I didn't realise that there was a new standardisation across all the keymaps to accommodate the configurator.

Hopefully fixed now.