Added new constructor for GraphServiceClient

fixes #2354

Fixes [#]2354(#2354)

-Allows Us to Overide the default Base URL in use cases such as GCC customers

Author: raghucha

src/main/java/com/microsoft/graph/beta/serviceclient/GraphServiceClient.java

@@ -64,6 +64,16 @@ public GraphServiceClient(@Nonnull AuthenticationProvider authenticationProvider
      */
     public GraphServiceClient(@Nonnull OkHttpClient client) {
         this(new AnonymousAuthenticationProvider(), client);
+    }
+     /**
+     * Instantiate the GraphServiceClient using an AuthenticationProvider, baseUrl and OkHttpClient.
+     * @param authenticationProvider The AuthenticationProvider for this GraphServiceClient.
+     * @param client The OkHttpClient for the GraphServiceClient.
+     * @param clouds The Clouds for the GraphServiceClient.
+     *
+     */
+    public GraphServiceClient(@Nonnull AuthenticationProvider authenticationProvider, @Nonnull OkHttpClient client, @Nonnull Clouds clouds) {
+        this(new BaseGraphRequestAdapter(authenticationProvider, clouds, "v1.0", getGraphClientOptions()));
     }
     /**
      * Instantiate the GraphServiceClient using a TokenCredential and Scopes.