[Keymap] Adding Custom Keymap for Let's Split (#9423)
* add
* Delete rules.mk
* Update keymap.c
* Update keymap.c
* Update keyboards/lets_split/keymaps/aerialviews007/keymap.c
* Update keyboards/lets_split/keymaps/aerialviews007/keymap.c
* Update keyboards/lets_split/keymaps/aerialviews007/keymap.c
* Update keyboards/lets_split/keymaps/aerialviews007/keymap.c
* Update keyboards/lets_split/keymaps/aerialviews007/keymap.c
* Update keyboards/lets_split/keymaps/aerialviews007/keymap.c
* Update keyboards/lets_split/keymaps/aerialviews007/keymap.c
* Update keyboards/lets_split/keymaps/aerialviews007/keymap.c