Implement remove root view operations

Summary: This diff implements the removal of react root view inside fabric cxx implementation

Reviewed By: shergin

Differential Revision: D8939942

fbshipit-source-id: 69835b55c80e2970d65220d947489bc1af4b125d

ReactAndroid/src/main/java/com/facebook/react/bridge/UIManager.java

@@ -12,6 +12,11 @@ public interface UIManager extends JSIModule, PerformanceCounter {
    */
   <T extends SizeMonitoringFrameLayout & MeasureSpecProvider> int addRootView(final T rootView);
 
+  /**
+   * Unregisters a new root view.
+   */
+  void removeRootView(int reactRootTag);
+
   /**
    * Updates the layout specs of the RootShadowNode based on the Measure specs received by
    * parameters.

ReactAndroid/src/main/java/com/facebook/react/fabric/FabricUIManager.java

@@ -547,6 +547,7 @@ public class FabricUIManager implements UIManager, JSHandler, FabricBinder {
   }
 
   public void removeRootView(int rootTag) {
+    mUIViewOperationQueue.enqueueRemoveRootView(rootTag);
     mRootShadowNodeRegistry.removeNode(rootTag);
   }