* Especially for splits, we need the ability to
unpair all paired devices as sledgehammer
if we need to "reset things", and doing so via
keymaps isn't suitable.
* Allows shields to define a collection of key
positions that if all held 2 seconds after
startup, will unpair all existing pairs for the
device.
* Service for split peripheral to report
position state to split central.
* Updated advertising info.
* Behavior for split BT until we have a proper
event system.
* 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