Use flag to control the hierarchy tree changes

This change includes these:
1. App languages
2.Regional preferences
2-1. Temperature
2-2. First day of week
2-3. Numbering system
3. Terms of address

Bug: 379962955
Flag: com.android.settings.flags.regional_preferences_api_enabled
Test: check hsv and atest TermsOfAddressCategoryControllerTest,
FirstDayOfWeekControllerTest, NumberingSystemControllerTest, TemperatureUnitControllerTest
Change-Id: I9ae376f24ac4d1cf9a186ad3d77b539ac4b83642

Change-Id: I1b2f508f618fba94e67b5f8b102620837a6dda1c