Add methods to simplify UptcMap usage.

Add a getOrCreate method so an object can be created if one doesn't
exist.
Add a new forEach method that will also supply the userId, packageName,
and tag to the consumer.

Bug: 135764360
Test: atest CountQuotaTrackerTest
Test: atest DurationQuotaTrackerTest
Change-Id: I9807fdd25ee2434e6c53b07cba4c0be7e5879237