Add CameraService Watchdog

This CL adds a watchdog used to detect issues in cameraservice/
Camera HAL. It uses a timer that can be customized to monitor calls
and kills the process if a fixed amount of time has elapsed without
a successful execution of the monitored call.

The following cases are included in this CL: flush(), close().
Further cases can be added with the APIs in watchdog.

Test: Manual; Tested by force triggering watchdog with custom timer
values and while(true) or sleep in monitored calls
Bug: 229145451
Merged-In: Ia7b4a3fd9395210800a391c62b4ea757efbb3b00

Change-Id: Ia7b4a3fd9395210800a391c62b4ea757efbb3b00