Time Zone data loader

- Use CountryZonesFinder to provide time zone id and region-to-timezone
  mapping, where the underlying data is updatable through an unbundled time zone
  data app in some devices.

Bug: 73952488
Bug: 72144448
Test: m RunSettingsRoboTests
Change-Id: I2e01e167c48987ebb98d4881a1a528d16dd82944