Added RCTJSINativeModule protocol to allow enabling JSI-bound nativemodule

Summary:
Instead of asking existing modules to implement `+allowJSIBinding`, introduce a temporary "empty" protocol so modules can just adopt it for migration purpose.

Eventually this protocol may just go away.

Modules need to adopt both `RCTBridgeModule` and `RCTJSINativeModule` for time being for backward compatibility.

p.s. the entire system isn't enabled yet, this is just some of the pre-reqs for NativeModule improvements.

Reviewed By: mmmulani

Differential Revision: D9762913

fbshipit-source-id: 470f640f11a5991e5cfa9c48a1931da660ebfcd2

React/Base/RCTBridgeModule.h

@@ -289,12 +289,6 @@ RCT_EXTERN void RCTRegisterModule(Class); \
  */
 + (BOOL)requiresMainQueueSetup;
 
-/**
- * Experimental.
- * If YES, this module will be set up via JSI binding instead.
- */
-+ (BOOL)allowJSIBinding;
-
 /**
  * Injects methods into JS.  Entries in this array are used in addition to any
  * methods defined using the macros above.  This method is called only once,
@@ -327,3 +321,12 @@ RCT_EXTERN void RCTRegisterModule(Class); \
 - (void)partialBatchDidFlush;
 
 @end
+
+/**
+ * Experimental.
+ * A protocol to declare that a class supports JSI-bound NativeModule.
+ * This may be removed in the future.
+ */
+@protocol RCTJSINativeModule <NSObject>
+
+@end

React/CxxBridge/RCTCxxBridge.mm

@@ -549,7 +549,7 @@ struct RCTInstanceCallback : public InstanceCallback {
   NSArray *moduleClassesCopy = [moduleClasses copy];
   NSMutableArray<RCTModuleData *> *moduleDataByID = [NSMutableArray arrayWithCapacity:moduleClassesCopy.count];
   for (Class moduleClass in moduleClassesCopy) {
-    if (RCTJSINativeModuleEnabled() && [moduleClass respondsToSelector:@selector(allowJSIBinding)] && [moduleClass allowJSIBinding]) {
+    if (RCTJSINativeModuleEnabled() && [moduleClass conformsToProtocol:@protocol(RCTJSINativeModule)]) {
       continue;
     }
     NSString *moduleName = RCTBridgeModuleNameForClass(moduleClass);