[WIP] DragonFist Legacy

Added support for Fabric mod loader!

The enhanced animations, movesets, and combat AI are disabled on Fabric, as Epic Fight is unsupported on Fabric yet.

Serves as a useful prototype for the Epic Fight project, and we will slowly adapt the solutions there to support Fabric (early WIP, without guaranteeing).

Once Epic Fight adds Fabric support (we're collaborating with the Epic Fight team lead), then it will be added for DragonFist Legacy addon as well.

This also makes the porting and updating for a more future-proof development.

Shifu boss is now hidden while not in training mode.

Stay tuned for more major updates (mod is still in early stages and incomplete).