[7.0] Add support for mavenizer output json, and expose mappings helper methods

[LexManos]

The initial design is to allow easier access to the mapping files for versions of minecraft that need renaming.

This is reliant on finalizing MinecraftForge/MinecraftMavenizer#15
Currently the json is just a Map<String, String> seems to work fine tho.

Changes the obfusication example from:

renamer.classes(jar) {
    mappings('net.minecraft:mappings_official:1.21.10-20251007.101210:map2srg@tsrg.gz')
}

to

renamer.classes(jar) {
    mappings(minecraft.instance().toSrg.get())
}

or

renamer.classes(jar) {
    map.from minecraft.instance().toSrgFile
}

The names of everything is just a quick pass, needs javadocs, etc..
This is a proof of concept so point out anything major you see wrong.

[Jonathing]

Looks good so far. Losing focus since it's getting late at night so I'd like to wait until I can do a second pass tomorrow morning.

Please fix the typos I pointed out. There aren't many.

[Jonathing]

this.extension.getProject()::file makes this illegal to be called during task execution. If it's not used in our tasks, in the future it would be most prudent to turn these into properties, since they can be finalized at the end of configuration time without hassle.

[LexManos]

As stated on discord, this is intended to be used as inputs to tasks, not in the task body. So in theory this should be perfectly safe and if it isn't then its on the modder for using it wrong.

[Jonathing]

If we are using Gson in Mavenizer, we should prefer using it in here as well. This is fine for now, though.

[LexManos]

I didnt want to add extra deps to FG as we are not using GSON for anything else currently.

[Jonathing]

FG already bundles Gson as it is a transitive dependency of JSON Data Utils. But not a big deal, we can revisit this as needed.

[LexManos]

Tempted to make MinecraftExtensionForProject extend MavenizerInstance to remove the need for the instance()

Functionally this works, just need to iterate the API as it exposes some that we need to be happy with.
Notiby:
minecraft.dependency functions get a String name first parameter, that defaults to default.
This name is the counterpart to minecraft.instance(String name) which gives you access to MinecraftInstance which is where all the getters for the output-json.

• getMappingVersion()
  The finalized version for the mapping, suitable for the dependency attributes, this is to expose the fixed-up parchment version string
• getDependency
  The dependency object mainly I exposed this incase I wanted to change the api to something like:

  minecraft.register("default", "net.minecraftfroge:forge:123")
  dependencies {
     implementation minecraft.instance().dependency
  }

• getToSrg() / getToObf()
  The artifact published by Mavenizer for mapping files to convert Mapped -> Srg/Obf.
  Ends up being something like net.minecraft:mappings_{channel}:{minecraft}-{mcp}:map2srg@tsrg.gz
• getToSrgFile() / getToObfFile()
  The full path to those artifacts, right now its in the cache folder not the output. But honestly it doesn't matter. This just allows for bypassing the gradle dependency resolution chain.

[Jonathing]

I've made a couple of notable changes to this PR. Minor, but substantial.

• MavenizerInstance now extends ProviderConvertible<ExternalModuleDependency>, which means that it itself can be used as the dependency in the dependencies { } block.
  • All minecraft.dependency methods now return MavenizerInstance instead of Provider<ExternalModuleDependency>.
  • MavenizerInstance#getDependency -> MavenizerInstance#asProvider.
• MinecraftExtensionForProject#instance -> MinecraftExtensionForProject#getDependency
  • This one is just a personal preference thing. Makes it cleaner and more consistent.

These changes change your proposed API from this:

renamer.classes(jar) {
    mappings(minecraft.instance().toSrg.get())
}

to this:

renamer.classes(jar) {
    mappings(minecraft.dependency.toSrg.get())
}

or this:

def minecraftDep = minecraft.dependency(libs.forge)

dependencies {
    implementation(minecraftDep)
}

renamer.classes(jar) {
    mappings(minecraftDep.toSrg.get())
}