Major code refactor, including a switch to Modrinth4J

[triphora]

This update should not have any breaking changes. However, it is very possible that it does, because this touches literally every part of Minotaur's codebase besides the dependency DSL. Over the course of the next few days, I will be testing this update on various projects using Minotaur to ensure that there are not any breaking changes.

If anyone wishes to test these changes out themselves, please do so:

1. Clone this repository and switch to this branch
2. Run gradle publishToMavenLocal
   a. If you run into issues, set EXCLUDE_SUBPROJECTS environment variable to true
3. Add mavenLocal() to the top of your project's pluginManagement.repositories block in settings.gradle if not already present
4. Optional: If you don't want your build to get pushed to the production server, set up a project on staging, set apiUrl = STAGING_API_URL in modrinth block, and set the other properties appropriately