* For now, to be used for FrankenKyria, where both
matrix halves will be attached to the same MCU, but
should be a stepping stone to proper split support
once we have a kscan driver over a split transport.
* Implement multiple instances for mock kscan driver.
* Move all headers to `include/zmk` directory.
* Update includes to reference them properly.
* Add `keymap.c` file from keymap, if found.
* Toplevel CONFIG_ZMK_BLE aggregate config setting.
Pete Johanson