feat(core): expose ViewRef as ChangeDetectorRef

closes #12722

This is helpful when manually dirty checking embedded views.

tools/public_api_guard/core/index.d.ts

@@ -1000,7 +1000,7 @@ export declare enum ViewEncapsulation {
 }
 
 /** @stable */
-export declare abstract class ViewRef {
+export declare abstract class ViewRef extends ChangeDetectorRef {
     destroyed: boolean;
     abstract onDestroy(callback: Function): any;
 }