Fixed for supporting mediaPlaybackRequiresUserAction under iOS 10. (#22208)

Summary:
There is a problem that the `mediaPlaybackRequiresUserAction` property does not work in WKWebView(`useWebKit`) under iOS 10.

I fully know you are currently working to migrate the core's WebView to the standalone `react-native-webview` project. This has already been submitted to PR in `react-native-webview` and will be merged soon. I hope this fix applies to `react-native` before your migration is done.
Pull Request resolved: #22208

Differential Revision: D13334868

Pulled By: cpojer

fbshipit-source-id: f2a811a477054155ed5fe62ab31e4d63f70e7848

Author: ifsnow

React/Views/RCTWKWebView.m

@@ -76,7 +76,9 @@ - (void)didMoveToWindow
     wkWebViewConfig.mediaTypesRequiringUserActionForPlayback = _mediaPlaybackRequiresUserAction
       ? WKAudiovisualMediaTypeAll
       : WKAudiovisualMediaTypeNone;
-   wkWebViewConfig.dataDetectorTypes = _dataDetectorTypes;
+    wkWebViewConfig.dataDetectorTypes = _dataDetectorTypes;
+#else
+    wkWebViewConfig.mediaPlaybackRequiresUserAction = _mediaPlaybackRequiresUserAction;
 #endif
 
     _webView = [[WKWebView alloc] initWithFrame:self.bounds configuration: wkWebViewConfig];