refactor(core): correct typing when getting the Nearest LContainer (#44087)

Updating the casted typings of `getNearestLContainer` to ensure that typescript properly
returns the LContainer | null type.

PR Close #44087

packages/core/src/render3/util/view_traversal_utils.ts

@@ -74,5 +74,5 @@ function getNearestLContainer(viewOrContainer: LContainer|LView|null) {
   while (viewOrContainer !== null && !isLContainer(viewOrContainer)) {
     viewOrContainer = viewOrContainer[NEXT];
   }
-  return viewOrContainer;
+  return viewOrContainer as LContainer | null;
 }