Provide a Test framework to test custom language server

[angelozerr]

Discussed in #548

^{Originally posted by RehanChalana September 29, 2024}
Hello Everyone,

I am working on a KCL-lang IntelliJ plugin utilizing LSP4IJ to implement Language Server Protocol (LSP) support.

Could anyone provide guidance or best practices for writing integration tests for a plugin using LSP4IJ?

Any advice, examples, or resources would be greatly appreciated!