Moving the project to be Kotlin-only

[StillLutto]

Note: the Java API will still be updated every Minecraft version, but additional features will not added.

This change is made for the sake of us, the developers, and the quality of the API itself. Making the API Kotlin-only will make it easier to implement Kotlin specific features and improve integration with Kotlin Coroutines. Making this change will be a massive improvement for the Kotlin side of the API.

How this will look

There will be two branches in the repository: one for Java, the other for Kotlin. The Java branch will only receive (Minecraft) version updates and some bug fixes; the Kotlin branch, which will become the master branch, will receive a full rewrite with a central focus on improving the experience for Kotlin and improving performance with Kotlin Coroutines.