Add DeviceConfig settings for loc. tz detection

Add DeviceConfig settings for location time zone detection.

Because the system_time namespace is intended for time AND time zone
detection, the DeviceConfig wrapper has been put in the timedetector
package.

The rest of the work is wiring the config flags to what they affect.

Bug: 178107773
Test: treehugger
Change-Id: Iabbd18f854a95e405d0bb1dcffd44ee86215e562