AudioUtils: Extract a generic event logger

This will allow us to use the same logging mechanism in not audio related
use cases, without the hard-codded and confusing "BT Audio" title.
This logger was also extended with 'logw' and 'loge' methods for
convenience.

Bug: 278964409
Test: atest BluetoothInstrumentationTests
Change-Id: If12dc7b429cc7d1b65be68971a389a7c96131762