Add command-line support for enabling auto time

Adds support for toggling the global auto time setting via the command
line. Useful for manual and automated tests, and also makes
time_detector consistent with time_zone_detector.

This also helps to confirm that the new config-update code should work
when used by SettingsUI.

Manually tested using a combination of the command line and SettingsUI.

Bug: 172891783
Bug: 229740080
Test: atest com.android.server.timedetector android.app.time
Test: adb shell cmd time_detector is_auto_detection_enabled
Test: adb shell cmd time_detector set_auto_detection_enabled
Change-Id: I39ce8c9381c2eef3f0fb5a42b54bc9c68e545f67