Moved the logic to select the type of reboot from behavior_reset.c to a
new zmk_reset() function. This allows rebooting to bootloader from
other code, and it gives us a starting point for future work to support
other bootloaders aside from the Adafruit nrf52 bootloader.
* GATT characteristic allowing passng data + behavior
label to invoke the behavior on the peripheral side.
* Behaviors have a locality setting to specify where they run.
* Build reset/power/RGB on peripheral.
* Use lesser-known DT features to skip behaviors not referenced
in the user keymap
* Update the behaviors to skip code if no nodes found.
* Remove some empty config/data structs where unused in
behaviors.
