Track SCO state in HfpClientDeviceBlock, and set SCO

state of both Connections and Conferences whenever they're created,
and when onAudioStateChanged is invoked.

Tag: #stability
Bug: 191206390
Bug: 190404030
Test: atest BluetoothInstrumentationTests
Change-Id: I46800c2d33e353362d3551b0742a42d2b179e6e4