fix(onShouldStartLoadWithRequest): android event was missing fields (#385)

`onShouldStartLoadWithRequest` event had only `url` in payload on android.
I've fixed it according to js event definition. 
https://github.com/react-native-community/react-native-webview/blob/master/js/WebViewTypes.js#L34

android/src/main/java/com/reactnativecommunity/webview/RNCWebViewManager.java

 
     @Override
     public boolean shouldOverrideUrlLoading(WebView view, String url) {
-      dispatchEvent(view, new TopShouldStartLoadWithRequestEvent(view.getId(), url));
+      dispatchEvent(
+          view,
+          new TopShouldStartLoadWithRequestEvent(
+                  view.getId(),
+                  createWebViewEvent(view, url)));
       return true;
     }
 
     @TargetApi(Build.VERSION_CODES.N)
     @Override
     public boolean shouldOverrideUrlLoading(WebView view, WebResourceRequest request) {
-      dispatchEvent(view, new TopShouldStartLoadWithRequestEvent(view.getId(), request.getUrl().toString()));
-      return true;
+      final String url = request.getUrl().toString();
+      return this.shouldOverrideUrlLoading(view, url);
     }
 
     @Override

android/src/main/java/com/reactnativecommunity/webview/events/TopShouldStartLoadWithRequestEvent.java

-package com.reactnativecommunity.webview.events;
-
-import com.facebook.react.bridge.Arguments;
-import com.facebook.react.bridge.WritableMap;
-import com.facebook.react.uimanager.events.Event;
-import com.facebook.react.uimanager.events.RCTEventEmitter;
-
-public class TopShouldStartLoadWithRequestEvent extends Event<TopMessageEvent> {
-    public static final String EVENT_NAME = "topShouldStartLoadWithRequest";
-    private final String mUrl;
-
-    public TopShouldStartLoadWithRequestEvent(int viewId, String url) {
-        super(viewId);
-        mUrl = url;
-    }
-
-    @Override
-    public String getEventName() {
-        return EVENT_NAME;
-    }
-
-    @Override
-    public boolean canCoalesce() {
-        return false;
-    }
-
-    @Override
-    public short getCoalescingKey() {
-        // All events for a given view can be coalesced.
-        return 0;
-    }
-
-    @Override
-    public void dispatch(RCTEventEmitter rctEventEmitter) {
-        WritableMap data = Arguments.createMap();
-        data.putString("url", mUrl);
-        data.putString("navigationType", "other");
-        rctEventEmitter.receiveEvent(getViewTag(), EVENT_NAME, data);
-    }
-}

android/src/main/java/com/reactnativecommunity/webview/events/TopShouldStartLoadWithRequestEvent.kt

+package com.reactnativecommunity.webview.events
+
+import com.facebook.react.bridge.WritableMap
+import com.facebook.react.uimanager.events.Event
+import com.facebook.react.uimanager.events.RCTEventEmitter
+
+/**
+ * Event emitted when shouldOverrideUrlLoading is called
+ */
+class TopShouldStartLoadWithRequestEvent(viewId: Int, private val mData: WritableMap) : Event<TopShouldStartLoadWithRequestEvent>(viewId) {
+    companion object {
+        const val EVENT_NAME = "topShouldStartLoadWithRequest"
+    }
+
+    init {
+        mData.putString("navigationType", "other")
+    }
+
+    override fun getEventName(): String = EVENT_NAME
+
+    override fun canCoalesce(): Boolean = false
+
+    override fun getCoalescingKey(): Short = 0
+
+    override fun dispatch(rctEventEmitter: RCTEventEmitter) =
+            rctEventEmitter.receiveEvent(viewTag, EVENT_NAME, mData)
+}