Implement an uptime tracker object

The purpose of UptimeTracker is to provide historical "how long has the system been alive for?"
information, across reboots and (within a tolerance factor) even crashes.

Bug: 32512551
Test: runtest -x packages/services/Car/tests/carservice_test/src/com/android/car/test/UptimeTrackerTest.java
Change-Id: I38b3f02cc3b222ebe9f602d20bbb3749cc89fbd8
2 files changed