Create language and region settings page

1. Use flag to control the UI migration
2. Create language_and_region_settings.xml for new UI migration.

Bug: 379962955
Flag: com.android.settings.flags.regional_preferences_api_enabled
Test: check hsv and atest LanguagePreferenceControllerTest
Change-Id: If8d2303a2a3061231e69d1a45ad432c061da3545

src/com/android/settings/language/LanguageSettings.java

@@ -25,6 +25,7 @@ import androidx.annotation.Nullable;
 
 import com.android.settings.R;
 import com.android.settings.dashboard.DashboardFragment;
+import com.android.settings.flags.Flags;
 import com.android.settings.search.BaseSearchIndexProvider;
 import com.android.settings.widget.PreferenceCategoryController;
 import com.android.settingslib.core.AbstractPreferenceController;
@@ -116,6 +117,9 @@ public class LanguageSettings extends DashboardFragment {
                 }
                 @Override
                 protected boolean isPageSearchEnabled(Context context) {
+                    if (Flags.regionalPreferencesApiEnabled()) {
+                        return false;
+                    }
                     return true;
                 }
             };