feat(Game): add toString method

Backported from commit: 016526486c
PR: #2313

src/structures/Presence.js

@@ -73,6 +73,14 @@ class Game {
     return this.type === 1;
   }
 
+  /**
+   * When concatenated with a string, this automatically returns the game's name instead of the Game object.
+   * @returns {string}
+   */
+  toString() {
+    return this.name;
+  }
+
   /**
    * Whether this game is equal to another game
    * @param {Game} game The game to compare with