Fix RCTNetworking yellow box

Summary:
Since `RCTNetworking` overrides init, it requires main queue setup. Native module infra currently throw a yellowbox if a module forgets it.

This diff fixes that.

{F361182429}

Changelog: [Internal]

Reviewed By: shergin

Differential Revision: D25962402

fbshipit-source-id: d847117cbfe0a191dc1882898711693c6fda68cd

Libraries/Network/RCTNetworking.mm

@@ -157,6 +157,11 @@ static NSString *RCTGenerateFormBoundary()
 
 RCT_EXPORT_MODULE()
 
++ (BOOL)requiresMainQueueSetup
+{
+  return YES;
+}
+
 - (instancetype)init
 {
   return [super initWithDisabledObservation];