Feature Request: Fake ModContainers

[LemmaEOF]

There are a good few projects built on Fabric that would do really well with being able to add ModContainers for the sake of adding representation for other mods/addons/plugins/etc. with loaders implemented on top of Fabric. Since Loader freezes after loading, there's not really a good place to add fake ModContainers without having to depend on a third-party lib, which a good few of these projects don't want to do. How feasible would it be to add a list of fake containers that don't get loaded by Fabric but are exposed for mods like ModMenu or anything else that would want to see these fake containers?

[i509VCB]

Related to PR #192