Enable the PiP tile in expanded spotlight layout to swap speakers without a layout shift

This was apparently left unimplemented during the first iteration of the TileStore. It's a welcome UI optimization and we can reliably test for it.

src/state/SpotlightExpandedLayout.ts

@@ -20,7 +20,7 @@ export function spotlightExpandedLayout(
 ): [SpotlightExpandedLayout, TileStore] {
   const update = prevTiles.from(1);
   update.registerSpotlight(media.spotlight, true);
-  if (media.pip !== undefined) update.registerGridTile(media.pip);
+  if (media.pip !== undefined) update.registerPipTile(media.pip);
   const tiles = update.build();
 
   return [