Having a separate NativeInterface facilitate to mock it and to not have
test relying on a uninitialized native

Bug: 295237486
Test: atest AvrcpControllerServiceTest
Test: atest AvrcpControllerStateMachineTest
Test: atest A2dpSinkStreamHandlerTest
Change-Id: I43b0ceeb9d6bf5b745686bd115da02b0c0be056c