Non-mod transitive dependencies are not loaded on Forge

[SquidDev]

This was originally https://github.com/cc-tweaked/CC-Tweaked/discussions/1752. I'm afraid I don't use Architectury myself, just reporting what feels like a bug.

Consider the following setup:

• Mod A depends on several non-mod jars. These are included in the the published mod (via jarjar) and also added as normal Maven dependencies.
• Mod B then adds a dependency on mod A.

On ForgeGradle, this works fine, because the dependencies are loaded via jarjar.

However, Architectury-Loom strips out jarjar metadata, instead assuming the jars will be loaded from the classpath. This works fine for actual mods, but because BSL/FML is A Bucket Of Fun, non-mod jars should be ignored entirely! This means that mod B needs to manually add of A's dependencies with forgeRuntimeLibrary!

[SquidDev]

Ideally it should be possible to infer forgeRuntimeLibrary automatically - the legacy classpath can just contain any dependency that doesn't contain a mods.toml or FMLModType in its META-INF.mf.

[Juuxel]

Sort of a duplicate of #58. It should be possible, but I think there are some non-mod classpath jars that get special treatment from Neo/Forge and would need to be excluded from an automatically generated forgeRuntimeLibrary.

[SquidDev]

"non-mod classpath jars that get special treatment from Neo/Forge" <- Oh, do you have any notes on this? I did a look through FML/BSL a few months back, and couldn't spot anything aside from FMLModType/mods.toml (and of course MOD_CLASSES), but may have missed something.

[Juuxel]

I was thinking of the libraries that are on the module path. Based on an example dev env though, they also seem to be present in the BSL classpath file, just with different versions (the module path has locked older versions while the BSL classpath has newer versions pulled in by Forge etc).