Declare official platform slice

Create the notion of an official platform slice.
This includes:
- Adding a second authority to the provider
- tagging slices in xml with a platform slice flag
- Including authority in the getUri method

Bug:73359139
Test: robotests
Change-Id: I5382be138a262dbc5a8324c34aab131c5d0d5516
Merged-In: I581ee6dfcdf935f452a15e89e5d055e375ff1877

src/com/android/settings/slices/SliceBroadcastReceiver.java

@@ -59,7 +59,8 @@ public class SliceBroadcastReceiver extends BroadcastReceiver {
                 // Wait a bit for wifi to update (TODO: is there a better way to do this?)
                 Handler h = new Handler();
                 h.postDelayed(() -> {
-                    Uri uri = SettingsSliceProvider.getUri(SettingsSliceProvider.PATH_WIFI);
+                    Uri uri = SliceBuilderUtils.getUri(SettingsSliceProvider.PATH_WIFI,
+                            false /* isPlatformSlice */);
                     context.getContentResolver().notifyChange(uri, null);
                 }, 1000);
                 break;