Interop: Create gating for the Bridge proxy

Summary:
The TurboModule interop layer on iOS will ship with a Bridge proxy.

The Bridge proxy is an object (see D46084318) that will try to simulate the Bridge's APIs, whenever possible, by delegating to Bridgeless abstractions.

## Changes
**Fact:** All FBiOS modules work with/without the bridge.

So, let's break down the Interop layer test group (i.e: interop on) into two groups:
- interop on, bridge proxy off
- interop on, bridge proxy on

## Benefits
This will speed up the production test, by allowing us to:
1. Isolate Interop issues to the bridge proxy faster.
2. Stabilize the TurboModule interop layer faster.

NOTE: This flag is temporary, and should be removed long-term: The TurboModule interop layer should ship with the bridge proxy enabled by default.

Changelog: [Internal]

Reviewed By: philIip

Differential Revision: D46088752

fbshipit-source-id: 1e161d49382635a44194166645c1a5d56d37b4de

packages/react-native/React/Base/RCTBridge.h

@@ -60,6 +60,10 @@ RCT_EXTERN void RCTDisableTurboModuleManagerDelegateLocking(BOOL enabled);
 RCT_EXTERN BOOL RCTTurboModuleInteropEnabled(void);
 RCT_EXTERN void RCTEnableTurboModuleInterop(BOOL enabled);
 
+// Turn on TurboModule interop's Bridge proxy
+RCT_EXTERN BOOL RCTTurboModuleInteropBridgeProxyEnabled(void);
+RCT_EXTERN void RCTEnableTurboModuleInteropBridgeProxy(BOOL enabled);
+
 // Route all TurboModules through TurboModule interop
 RCT_EXTERN BOOL RCTTurboModuleInteropForAllTurboModulesEnabled(void);
 RCT_EXTERN void RCTEnableTurboModuleInteropForAllTurboModules(BOOL enabled);

packages/react-native/React/Base/RCTBridge.m

@@ -130,6 +130,17 @@ void RCTEnableTurboModuleInterop(BOOL enabled)
   turboModuleInteropEnabled = enabled;
 }
 
+static BOOL turboModuleInteropBridgeProxyEnabled = NO;
+BOOL RCTTurboModuleInteropBridgeProxyEnabled(void)
+{
+  return turboModuleInteropBridgeProxyEnabled;
+}
+
+void RCTEnableTurboModuleInteropBridgeProxy(BOOL enabled)
+{
+  turboModuleInteropBridgeProxyEnabled = enabled;
+}
+
 static BOOL useTurboModuleInteropForAllTurboModules = NO;
 BOOL RCTTurboModuleInteropForAllTurboModulesEnabled(void)
 {