Implementation of textDocument.callHirearchy

[Frityet]

https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_prepareCallHierarchy

[AkshaySG14]

Hi folks. Thank you for all the great work on the Lua LSP! We were wondering what the lift is on getting the prepare call hierarchy LSP spec to work for this language server.

I am building an IDE called Haystack (https://haystackeditor.com/) that uses the call hierarchy for one of its main features, and folks would really love if this could be built in Lua so that Haystack could work better with Lua!

Happy to help in any way to get this done.

[CppCXY]

It seems similar to findReferences, but the result is the containing function. However, I guess the author probably won't implement this feature. You might consider make a PR.