Animated JS: clear out component refs on unmount

Summary:
"The instance should not stick around after unmount..." - Tim Yung, 2021

I have a hypothesis that, if a component instance of an animated component sticks around after unmount, it could cause memory leaks due to references to Fabric ShadowNodes across the JSI (this would not impact non-Fabric... in theory).

Wild guess. If OOMs disappear then maybe this hypothesis is correct, but it's a long shot. I figure there's ~no harm in doing this cleanup here anyway.

Changelog: [Internal]

Reviewed By: sammy-SC

Differential Revision: D26650348

fbshipit-source-id: 90633db650b65755cacfb52344e7b53e46c9b125

Libraries/Animated/createAnimatedComponent.js

@@ -299,6 +299,8 @@ function createAnimatedComponent<Props: {+[string]: mixed, ...}, Instance>(
       this._propsAnimated && this._propsAnimated.__detach();
       this._detachNativeEvents();
       this._markUpdateComplete();
+      this._component = null;
+      this._prevComponent = null;
     }
   }