Transition from Architectury to Multi-Loader

[Straywave]

Adapt template to only use ForgeGradle and Fabric Loom, like jaredlll08's Multi Loader Template.

Benefits:

• Cutting out unnecessary dependencies is always a plus
• Architectury's abstractions aren't really used much

Drawbacks:

• Gradle config becomes more complicated
• Doing multi-platform stuff will be slightly trickier
• No abstractions across both modding platforms