Add test for setDeviceConnectionState.

The test uses HDMI and bt hfp to test setting of device connection
state. After the device is connected, the test tries to use explicit
routing to the new connected device to make sure the connection state is
set correctly.

Bug: 135621476
Test: atest audiopolicy_tests
Change-Id: I14759daac6d3522fa133a6e3b27b3863bb4ce3d1