Refactored Bluetooth support to make adding new Bluetooth modules
easier in the future.
* Remove `OUT_BLE` key from QMK's keymap. `OUT_BT` is all we need now
as there's no difference anymore.
* Made BLUETOOTH_ENABLE build option legacy as not to break existing
keymaps (Falls back to existing EZ Key support if on)
* Removed `ADAFRUIT_BLE_ENABLE` build option
* Created new build option `BLUETOOTH` with module option (Currently
`AdafruitEZKey` & `AdafruitBLE`)
* Moved all LUFA bluetooth key/mouse events under `BLUETOOTH_ENABLE`
ifdef with selected modules output.
