Improve info about location algorithm status

Be more informative about location algorithm status than "unknown": It's
possible for the time zone detector to tell when the location algorithm
is supported, not running, or running (but not yet reported an event).

Bug: 236624675
Test: atest services/tests/servicestests/src/com/android/server/timezonedetector/
Change-Id: I1cf569efe1f00cfa2faee02f76b84a71a68fb8ad