Enable BVRA client

Add implementation to startVoiceRecognition and stopVoiceRecognition.

Bug: 38485187
Test: act.py -tc BtCarHfpTest:test_bluetooth_voice_recognition_assistant
Change-Id: Icdecdb41c0353871ca1afc32b2d7ffa01172c0c3
(cherry picked from commit a323e1643d6a01be7cec16eeaa65b281acbcd941)
5 files changed