gd: Handle LE advertisement tracking sub-event

* Handle LE advertisement tracking sub-event
* Handle Storage threshold sub-event

Tag: #gd-refactor
Bug: 186234480
Test: gd/cert/run
Test: bluetooth_test_gd
Test: sl4a, BleOnLostOnFoundTest
BYPASS_LONG_LINES_REASON: Bluetooth likes 120 lines

Change-Id: Idfcd8f68d2a2fa6b8633579e0c25bc3b07536f76