Blueberry: Migrate GattNotifyTest and GattConnectTest to Mobly

* Migrate legacy ACTS-based tests to the new Blueberry mobly based
  framework:
      GattNotifyTest
      GattConnectTest
* Add associated libraries to support these tests
* client_port is no longer needed in config file

Test: gd/cert/run --sl4a_sl4a
Test: gd/cert/run --sl4a
Tag: #stability
Bug: 232048916
Change-Id: I680661d75dcd203c3f050b3379a01523275ec5b7