Unify tag namespace and conventions between Neoforge and Fabric (and Quilt) for 1.21 MC

[sylv256]

FabricMC/fabric#3310

If Fabric implements this, we will probably have to. It's a good system anyways, so I don't see any problem with Quilt-exclusive mods using it. If we don't want to implement it for Quilt-exclusive mods, we could just use a system to convert their tags to ours. Again though, I think we should implement this both for compatibility and because it's beneficial to modding.

But a mod could be called common!

Okay, then we should reserve that namespace then (with the exception of Fabric mods unless Fabric reserves common).

[F5T3]

You literally just took the comments from the original pull and reworded them so that it looks original, and why did you make two issues? Oh, one is in QuiltMC and this one is in this repo.

[sylv256]

Oh, one is in QuiltMC and this one is in this repo.

I think you meant Fabric, but yes, this is a mirror of Fabric's issue.