Update MockBukkit to 1.20.4 along with existing tests

[J3fftw1]

Description

This PR updates mockbukkit.
It was a huge pain

Proposed changes

Make main class not final
Changed dependency order(this apparently matters a lot. Dont ask me why)
Changed grass material to grass_block. in 1.20.4 grass isnt a thing anymore. We should be using grass only in mocks so this shouldnt effect anything

Related Issues (if applicable)

Checklist

• I have fully tested the proposed changes and promise that they will not break everything into chaos.
• I have also tested the proposed changes in combination with various popular addons and can confirm my changes do not break them.
• I have made sure that the proposed changes do not break compatibility across the supported Minecraft versions (1.16.* - 1.20.*).
• I followed the existing code standards and didn't mess up the formatting.
• I did my best to add documentation to any public classes or methods I added.
• I have added Nonnull and Nullable annotations to my methods to indicate their behaviour for null values
• I added sufficient Unit Tests to cover my code.

ToDo

• Write up a doc on how to continue forward with mockbukkit
• Fix all tests
• Clean up pom.xml, restructure it
  • Update dough
  • Update MockBukkit
• Possibly remove the comma true/ new constructor in main class
• Update Spigot to 1.20.4 or later if later releases before merge
• Rewrite history

[github-actions]

Your Pull Request was automatically labelled as: "🧹 Chores"
Thank you for contributing to this project! ❤️

[github-actions]

Slimefun preview build

A Slimefun preview build is available for testing!
Commit: 43d99917

https://preview-builds.walshy.dev/download/Slimefun/4086/43d99917

Note: This is not a supported build and is only here for the purposes of testing.
Do not run this on a live server and do not report bugs anywhere but this PR!

[Sfiguz7]

Other than what I committed above all looks good, check it again and if it's ok we're golden