unique -> shared pointer in Component

Summary:
Refactor unique -> shared pointer in Component. This will be necessary in the next diffs of the stack

changelog: [intenal] internal

Differential Revision: D41629759

fbshipit-source-id: 335161c350692e25ac3443bd19675a89f9df60c4

ReactAndroid/src/main/jni/react/cxxcomponents/ComponentManager.h

@@ -21,7 +21,7 @@ class ComponentManager {
       Tag tag,
       Props::Shared initialProps) = 0;
 
-  virtual std::unique_ptr<Component> createComponent(Tag tag) = 0;
+  virtual std::shared_ptr<Component> createComponent(Tag tag) = 0;
 
   virtual ~ComponentManager() = default;
 };