Add KC_CPNL, KC_ASST, KC_MCTL, and KC_LPAD

[Dreista]

As title.

See https://github.com/qmk/qmk_firmware/blob/422d502903c43c19007c95e6206d34f22da63092/docs/keycodes_basic.md?plain=1#L224

Related: #190

[xyzz]

I'm pretty sure at least mission control/launchpad aren't supported on protocol v5. So you shouldn't put them there, and we need to make sure they don't appear in the ui when using with such older boards.

[Dreista]

Ahh I see. Need to remove the keycodes from keycodes_v5.py then figure out how to handle the case where keycode is not present in keycodes_v5.py appropriately.