Adding availability support to VMS subscribers

Test: runtest -v -x carservice_unit_test/src/com/android/car/VmsRoutingTest.java
      runtest -v -x carservice_test/src/com/android/car/test/VmsSubscriberManagerTest.java
      runtest -v -x carservice_test/src/com/android/car/test/VmsPublisherSubscriberTest.java
      runtest -v -x carservice_test/src/com/android/car/test/VmsPublisherClientServiceTest.java

Change-Id: I3570dc902a020463f1041f04fa31267fbdab39c0
11 files changed