Updated existing cordova.exec method signature.

Documentation reference for change context:

https://cordova.apache.org/docs/en/latest/guide/hybrid/plugins/index.html#the-javascript-interface

cordova/cordova.d.ts

@@ -35,7 +35,7 @@ interface Cordova {
      * @param action The action name to call on the native side (generally corresponds to the native class method).
      * @param args An array of arguments to pass into the native environment.
      */
-    exec(success: () => any, fail: () => any, service: string, action: string, args?: any[]): void;
+    exec(success: (data: any) => any, fail: (err: any) => any, service: string, action: string, args?: any[]): void;
     /** Gets the operating system name. */
     platformId: string;
     /** Gets Cordova framework version */