fix(types): wrong parameter type in onLoadProgress (#538)

WebViewProgressEvent musst be wrapped within NativeSyntheticEvent

src/WebViewTypes.ts

   lockIdentifier: number;
 }
 
-export interface WebViewProgressEvent extends WebViewNativeEvent {
+export interface WebViewNativeProgressEvent extends WebViewNativeEvent {
   progress: number;
 }
 
 
 export type WebViewEvent = NativeSyntheticEvent<WebViewNativeEvent>;
 
+export type WebViewProgressEvent = NativeSyntheticEvent<WebViewNativeProgressEvent>;
+
 export type WebViewNavigationEvent = NativeSyntheticEvent<WebViewNavigation>;
 
 export type WebViewMessageEvent = NativeSyntheticEvent<WebViewMessage>;