Move Time servicestests to their own test module

Move Time servicestests to their own test module to handle
http://b/305192485 (inability to land TEST_MAPPING changes because
FrameworksServicesTests is perma-broken).

Some javadocs and other non-functional changes have been made to test
source to keep checkstyle happy.

Bug: 305192485
Bug: 182461754
Test: Treehugger
Test: atest FrameworksTimeServicesTests
Change-Id: I8592632388b0225aba17c254b8c871c2f1b1aeca