Migration to PacketEvents (depends on https://github.com/HibiscusMC/HibiscusCommons/pull/12)

[OakLoaf]

Select the option(s) that best describes this PR:

• Major breaking change
• Minor change
• Feature implementation
• Bug fix
• Chore (Changes that don't fix or add new features and don't modify source files)
• Refactoring (Changes that dont't fix or add new features but do modify source files)
• Documentation (Changes to README files and/or JavaDocs)
• Style (Changes that don't affect the meaning of the code)
• Performance
• Other (Please specify below)

Please describe the changes this PR makes and why it should be merged:

Check that:

• Any new classes, public methods and/or properties are properly documented with JavaDocs
• Syntax and style are consistent with existing code
• Any replaced method isn't deleted, but rather labeled as deprecated

Note In the case where the new method has the exact same signature as the method it's replacing, mention above that the old method was deleted.

This PR focuses on moving over to PacketEvents from ProtocolLib, I've given more detail about reasons for changes in the HibiscusCommons PR, of which this PR depends on.

This PR could contain breaking changes for dependencies, although the methods/classes that have been deleted in this PR all appear to be intended for internal use. Unfortunately, keeping the methods/classes wasn't particularly a possibility without creating some form of packet converter which would've been a large amount of work for what is likely to be unused outside of the project.

It is important to note that this PR has only been tested on 1.21.1 so testing is very much needed.