Mappings support

[Earthcomputer]

This PR is currently unfinished, and exists so that zml doesn't have to type a URL into the address bar.

[zml2008]

tossing some notes here on how I think we'll get to a releasable state given FART can't be on the buildscript classpath as-is:

• Add ServiceLoader discovery for transformers to FART
• run remapping jobs in classloader-isolation workers
• ship a relocated version of SrgUtils with VanillaGradle in-jar, used to build mappings files
• split out any custom transformers we use as separate artifacts that are then placed in the fartTransformers configuration of the target project

that's not ideal since things get weird with multi-project builds, but it does make things work

also, having an isolated remapper classpath allows us to fully capture the code inputs and regenerate artifacts if any of those inputs change, maybe?

[oliviathevampire]

How functional is this?

[Tslat]

It's really sad this still isn't a thing

Any chance we can revive it in a renewed form?

This is arguably one of the most requested features for VG

Edit: lol nice, marked as spam Real mature guys

[AdamCalculator]

mmm???