Fight Picker - Now Merged into Rush

It's a small but very much needed update. I have cleaned up the code and made it feel MUCH better without changing the mechanics much.

-Cleaned up code (using the attribute system for the knockback now instead of a custom method). as a bonus i have made it so that the knockback now also applies with the item in your offhand!

-New particle effects for the leap. There will now be warden sonic boom particles under the player right as the item is used!

-New sound effects for the leap. The warden sonic boom sound effect will play when the item is used now (along with a cape fling-like sound). It now feels infinitely more cool to use this item thanks to the effects!