don't require SwapChain to be passed to viewer.render - this will just render into all registered swapchains

thermion_dart/lib/src/filament/src/interface/filament_app.dart

@@ -203,8 +203,8 @@ abstract class FilamentApp<T> {
   ///
   ///
   ///
-  Future setMaterialInstanceAt(
-      ThermionEntity entity, int primitiveIndex, MaterialInstance materialInstance);
+  Future setMaterialInstanceAt(ThermionEntity entity, int primitiveIndex,
+      MaterialInstance materialInstance);
 
   ///
   ///
@@ -216,6 +216,11 @@ abstract class FilamentApp<T> {
   ///
   Future unregister(covariant SwapChain swapChain, covariant View view);
 
+  ///
+  ///
+  ///
+  Future<Iterable<SwapChain>> getSwapChains();
+
   ///
   ///
   ///