New Custom Game Mode - URF

URF mode should be set as a new permanent game mode for Custom games, which saves a lot of our times for new experiments and more fun custom games!

URF mode shouldn't be a permanent game mode, but a permanent game mode in Custom can bring many great things we can experiment and play with shorter cooldown of abilities.

There's one more thing to say that I think it'd be great if we could choose either URF or Non-URF mode when we're creating the custom game.

In other words, URF game mode shouldn't appear on the Custom Game category, but more like it's something we can set before we creating a room.