Introduce Capability system

[miozune]

This PR introduces Capability system.

For those who don't know about Capability

Please read Javadoc. If there's anything unclear, feel free to ask questions.

For those who are familiar with Capability in later MC versions

This PR was originally based on 1.12.2 Forge implementation. After that Raven's suggestion drastically simplified it. Now Capability class is gone and there're only CapabilityProvider and Capabilities.

Side note, due to skill issue I used generative AI to generate documents. While I used multiple models, read everything they outputted and tweaked sentences, there could still be oddities.

[eigenraven]

The docs definitely need rewording as they're quite confusing in places, I'll try to do it later today

[Caedis]

Some examples like for some vanilla stuff would be useful

[github-actions]

Warning: 2 uncommitted changes
pull request create failed: GraphQL: Head sha can't be blank, Base sha can't be blank, Head repository can't be blank, No commits between GTNewHorizons:feature/capability and origin:GTNewHorizons-feature/capability-spotless-fixes, Head ref must be a branch, not all refs are readable (createPullRequest)

[miozune]

Now it's reworked and significantly simplified thanks to Raven. Please take another look.

Some examples like for some vanilla stuff would be useful

As written on Javadoc, usage of vanilla/Forge interfaces as capability is discouraged.