Cert for HAL adapter

Introducing cert framework and a simple test case for HCI HAL
transportation adapter

Test-prerequisite: gRPC python. Install from pip
(https://grpc.io/blog/installation)

Test: 1. start HCI rootcanal or HIDL transport
      $ANDROID_HOST_OUT/nativetest64/root-canal/root-canal
      2. start stack with facade
      $ANDROID_HOST_OUT/bin/stack_with_facade
      3. run a simple test case
      $ANDROID_HOST_OUT/nativetest64/bluetooth_cert_test/bluetooth_cert_test

Or: One-liner: python cert/run_cert.py

Change-Id: I3cf2f54605ce2709d1c149b1221dedc8dc5dca92