Allow RCTRootView users to require NativeModules without the bridge

Summary:
RCTRootVeiw exports the bridge. One reason why is to allow users of RCTRootView users to access NativeModules.

## Changes
- RCTBridge now exports the RCTModuleRegistry
- RCTRootView now exports the RCTModuleRegistry exported by the bridge
- Users of RCTRootView use the RCTModuleRegistry exported by RCTRootView to access NativeModules

## Benefits
Down the line, we'll change how RCTRootView gets the RCTModuleRegistry (i.e: it won't use the bridge in bridgeless mode).

Changelog: [Internal]

Reviewed By: sammy-SC

Differential Revision: D30434886

fbshipit-source-id: 875fce24d2fd9ee6350f128c8612e613e61e390e

React/Base/RCTBridge+Private.h

@@ -7,6 +7,7 @@
 
 #import <React/RCTBridge.h>
 
+@class RCTModuleRegistry;
 @class RCTModuleData;
 @protocol RCTJavaScriptExecutor;
 
@@ -62,6 +63,13 @@ RCT_EXTERN void RCTRegisterModule(Class);
  */
 @property (nonatomic, strong, readwrite) NSURL *bundleURL;
 
+/**
+ * An object that allows one to require NativeModules/TurboModules.
+ * RCTModuleRegistry is implemented in bridgeless mode and bridge mode.
+ * Used by RCTRootView.
+ */
+@property (nonatomic, strong, readonly) RCTModuleRegistry *moduleRegistry;
+
 @end
 
 @interface RCTBridge (RCTCxxBridge)

React/Base/RCTBridge.m

@@ -257,6 +257,11 @@ RCT_NOT_IMPLEMENTED(-(instancetype)init)
   });
 }
 
+- (RCTModuleRegistry *)moduleRegistry
+{
+  return self.batchedBridge.moduleRegistry;
+}
+
 - (NSArray<Class> *)moduleClasses
 {
   return self.batchedBridge.moduleClasses;

React/Base/RCTRootView.h

@@ -8,6 +8,8 @@
 #import <UIKit/UIKit.h>
 
 #import <React/RCTBridge.h>
+#import <React/RCTBridgeModule.h>
+#import <React/RCTEventDispatcherProtocol.h>
 
 @protocol RCTRootViewDelegate;
 
@@ -80,6 +82,12 @@ extern
  */
 @property (nonatomic, readonly) BOOL hasBridge;
 
+/**
+ * This API allows users of RCTRootView to access other NativeModules, without
+ * directly accessing the bridge.
+ */
+@property (nonatomic, strong, readonly) RCTModuleRegistry *moduleRegistry;
+
 /**
  * The name of the JavaScript module to execute within the
  * specified scriptURL (required). Setting this will not have

React/Base/RCTRootView.m

@@ -121,6 +121,11 @@ RCT_NOT_IMPLEMENTED(-(instancetype)initWithCoder : (NSCoder *)aDecoder)
   return _bridge != nil;
 }
 
+- (RCTModuleRegistry *)moduleRegistry
+{
+  return _bridge.moduleRegistry;
+}
+
 #pragma mark - passThroughTouches
 
 - (BOOL)passThroughTouches

React/Base/Surface/SurfaceHostingView/RCTSurfaceHostingProxyRootView.h

@@ -27,6 +27,7 @@ NS_ASSUME_NONNULL_BEGIN
 @property (nonatomic, copy, readonly) NSString *moduleName;
 @property (nonatomic, strong, readonly) RCTBridge *bridge;
 @property (nonatomic, readonly) BOOL hasBridge;
+@property (nonatomic, strong, readonly) RCTModuleRegistry *moduleRegistry;
 @property (nonatomic, copy, readwrite) NSDictionary *appProperties;
 @property (nonatomic, assign) RCTRootViewSizeFlexibility sizeFlexibility;
 @property (nonatomic, weak) id<RCTRootViewDelegate> delegate;

React/Base/Surface/SurfaceHostingView/RCTSurfaceHostingProxyRootView.mm

@@ -10,6 +10,7 @@
 #import <objc/runtime.h>
 
 #import "RCTAssert.h"
+#import "RCTBridge+Private.h"
 #import "RCTBridge.h"
 #import "RCTLog.h"
 #import "RCTPerformanceLogger.h"
@@ -98,6 +99,11 @@ static RCTRootViewSizeFlexibility convertToRootViewSizeFlexibility(RCTSurfaceSiz
   return _bridge != nil;
 }
 
+- (RCTModuleRegistry *)moduleRegistry
+{
+  return _bridge.moduleRegistry;
+}
+
 RCT_NOT_IMPLEMENTED(-(instancetype)initWithFrame : (CGRect)frame)
 RCT_NOT_IMPLEMENTED(-(instancetype)initWithCoder : (NSCoder *)aDecoder)
 

React/CxxBridge/RCTCxxBridge.mm

@@ -244,6 +244,11 @@ struct RCTInstanceCallback : public InstanceCallback {
 @synthesize performanceLogger = _performanceLogger;
 @synthesize valid = _valid;
 
+- (RCTModuleRegistry *)moduleRegistry
+{
+  return _objCModuleRegistry;
+}
+
 - (void)setRCTTurboModuleRegistry:(id<RCTTurboModuleRegistry>)turboModuleRegistry
 {
   _turboModuleRegistry = turboModuleRegistry;