Alpha Release for Minecraft 1.21.1

This is a mostly-unmolested forward-port of Suspicious Shapes to 1.21.1. for the most part, resource packs designed for the original will work in the updated version.

Previously, Suspicious Shapes would ignore models parented to a gltf without the key-value pair,

"loader": "suspicious_shapes:gltf"

The new version has namespaced this key to be less intrusive when loaded alongside connector and/or the upcoming fabric model loader API. Models should be updated as follows:

"suspicious_shapes:loader": "suspicious_shapes:gltf"

Sorry for the difficulty this may cause, but I promise it'll be worth the trouble with all the wild new mod interactions this makes possible.