Fabric: Making UIView+ComponentViewProtocol to conform to the protocol

Summary:
UIView+ComponentViewProtocol is useless without it. Conformance to the protocol is only purpose of this category.
We didn't run into this issue because we have never used that yet.

Reviewed By: mdvacca

Differential Revision: D15419953

fbshipit-source-id: 84a430397e886c941d35075d9754eae5748c3a3f

Author: shergin

React/Fabric/Mounting/UIView+ComponentViewProtocol.h

@@ -14,7 +14,7 @@ NS_ASSUME_NONNULL_BEGIN
 /**
  * Default implementation of RCTComponentViewProtocol.
  */
-@interface UIView (ComponentViewProtocol)
+@interface UIView (ComponentViewProtocol) <RCTComponentViewProtocol>
 
 + (std::vector<facebook::react::ComponentDescriptorProvider>)supplementalComponentDescriptorProviders;
 

React/Fabric/Mounting/UIView+ComponentViewProtocol.mm

@@ -17,6 +17,12 @@
 
 @implementation UIView (ComponentViewProtocol)
 
++ (ComponentDescriptorProvider)componentDescriptorProvider
+{
+  RCTAssert(NO, @"`-[RCTComponentViewProtocol componentDescriptorProvider]` must be implemented in a concrete class.");
+  return {};
+}
+
 + (std::vector<facebook::react::ComponentDescriptorProvider>)supplementalComponentDescriptorProviders
 {
   return {};