Show Inlay Hints in VSCode for all open files

[Zentrik]

Currently the VSCode Inlay hints only show up for the file in which the method we are descending on is defined. It would be nice to show hints for all open files, this would require a function being added to the VSCode extension to expose the open files. Alternatively, we could hack around it by showing hints for all files in a package. I'm hesitant to show hints in all files as that would probably slow things down a lot.

Relevant line in source code https://github.com/JuliaDebug/Cthulhu.jl/blob/575a73286598b69c4da9fdd91b63b0ef5480d83d/src/codeview.jl#L360-L361