Refactor UnityInstance type declaration to include Quit method for improved functionality

Author: jeffreylanters

module/source/types/unity-instance.d.ts

@@ -5,10 +5,13 @@ import { UnityModule } from "./unity-module";
 /**
  * Type declaration for the UnityInstance.
  */
-type UnityInstance = Pick<
-  UnityModule,
-  "SendMessage" | "SetFullscreen" | "Quit"
-> & {
+type UnityInstance = Pick<UnityModule, "SendMessage" | "SetFullscreen"> & {
+  /**
+   * Quits the Unity WebGL application and removes it from the memory.
+   * @returns a promise which resolves when the application did quit.
+   */
+  Quit(): Promise<void>;
+
   /**
    * The internal Unity Module.
    */