BLE: Show name of device which is connected / is trying to pair

Tries to read the device name of the central via the GAP Device Name characteristic. If there is a device name available, it will be shown on the screen. Even if it only becomes available at a later time during pairing.

This is how it looks now:

preload/apps/ble/__init__.py

@@ -14,6 +14,7 @@ STATE_NUMERIC_COMPARISON = 2
 STATE_WAIT_FOR_COMPLETION = 3
 STATE_FAIL = 4
 
+
 def ble_callback(_):
     global ble_event
     ble_event = sys_ble.get_event()