3.0 - Full rewrite, Gradle 9, Java-centric API

[Jonathing]

GradleUtils 3.0 refocuses itself on being a lightweight Gradle plugin with the intent of providing some additional functionality for consumers.

Shared Utilities

GradleUtils now includes a public package, net.minecraftforge.gradleutils.shared, that is designed to be used by our plugins to reduce duplicate code and standardize how they operate.

Git Version Plugin split

Git Version is no longer included and is now an optional integration. It will be developed in the gradle-plugin folder in MinecraftForge/GitVersion. This also includes the changelog functionality.

Git Version: net.minecraftforge.gitversion
Git Changelog: net.minecraftforge.changelog

• A lot of the code in GradleUtils implicitly references it using @CompileDynamic to avoid a hard dependency on it. The Git Version plugin depends on GradleUtils which would cause a circular dependency.
• Functionality that requires the presence of Git Version (workflow YAML generation, PomUtils#addRemoteDetails(MavenPom) without the URL) will now display warnings or throw errors if net.minecraftforge.gitversion is not applied.

API Restructuring

The API is exclusively in Java and will now play nice with JavaDocs and DSL linting (Groovy and Kotlin).

The only code in the plugin that uses Groovy are internal implementations that cannot be accessed publicly.

[Jonathing]

This is now ready for review. I've edited the description to account for recent changes. I will likely commit this with the tag 3.0-beta sometime this evening or tomorrow to get the ball rolling.

[LexManos]

Nothing in the code is jumping out at me as wrong.
But my eyes glaze over when it comes to gradle stuff.
Only thing I would suggest is writing a central readme/features file that explicitly states what we intend to be public and thus need to support feature wise.
Anything else is internal/can break.