Make CTS tests ambivalent to server impl

Implement shell command test support that will work regardless of which
of the two location NetworkTimeHelper implementations is in use at the
time. This is to prevent CTS breaking if OEMs or form factors switch the
implementation to the new one during the next Android release cycle.

New shell commands have been added temporarily to support the new
SystemClockNetworkTimeTest and do the right thing depending on the
implementation in use. This avoids the need for the tests to know which
impl is in use. In a future release cycle, when the old impl is deleted
these shell commands can be removed and the test changed as the new impl
uses the time_detector and suitable commands (mostly) exist for other
reasons.

Bug: 222295093
Test: atest services/tests/servicestests/src/com/android/server/timedetector/TimeDetectorServiceTest.java
Test: See associated CTS change
Change-Id: Icca02ec263bb20bc02a0dd6dd6cc13342d9e4e7b