Update ClusterHomeActivityLightMode to send heartbeats.

To demostrate how ClusterHomeManager health monitoring API is used,
ClusterHomeActivityLightMode#onStart now calls
startVisibilityMonitoring(). Also it calls sendHeartbeat() every 10
seconds to send heartbeat signals.

Bug: 302368365

Test: adb shell dumpsys car_service --service ClusterHomeService
      adb logcat CAR.CLUSTER ClusterHomeActivityLightMode *:S

Change-Id: Ie737a98cf852a1e18a0b0591a0fcc9276800cead
1 file changed
tree: 96f01723e0f6647360d1915f54f39c03f40abba9
  1. ClusterHomeSample/
  2. ClusterOsDouble/
  3. DirectRenderingCluster/