3.0 - API restructuring and Deprecation removals

[Jonathing]

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

• Proper separation of API into public interfaces to be used by consumers.
  • This is identical to how I've been writing ForgeGradle 7.
• Removed all deprecated APIs (except for the teamcity task).
• All 3 plugins are now fully isolated (will convert into subprojects later).
  • PomUtils in GradleUtils has optional functionality with the gitversion plugin, but is not required for the plugin to work and apply correctly. See PomUtils#addRemoteDetails(MavenPublication).
• Targetting Gradle 9 (will target latest Gradle 8 until it releases).
  • This includes the usage of incubating APIs such as Problems and BuildLayout.
• Made the code not ass.

Still heavily work-in-progress, and also see #19 for the idea of moving the gitversion and changelog plugins to MinecraftForge/GitVersion.

• Closes Move artifact promotion from SharedActions to GradleUtils #20.