GD-HCI: Add verbose logging for Tx and Rx packets

* Add StringFormat method
* Add verbose logging in GD Android HIDL client for every outgoing
  HCI transmission and incoming HCI transmission

Bug: 164973960
Test: make, atest bluetooth_test_gd, listen to music
Tag: #gd-refactor
Change-Id: I1b12c0180b835d9a0f3f641d80b62131e5b72fd4