Replace go-lsp with gopls/internal/protocol

[jwong-beep]

Sourcegraph's go-lsp has been archived is a no longer updated to reflect the latest LSP protocol. Let's switch to Gopls' implementation so we can get some of the new types and methods to unlock new features and bug fixes.

https://pkg.go.dev/golang.org/x/tools/gopls@v0.21.0/internal/protocol

[peterebden]

I don't believe we can make use of that package? It's an internal package so nothing outside golang.org/x/tools/gopls can import it (c.f. https://pkg.go.dev/cmd/go#hdr-Internal_Directories)

Would make sense to swap out go-lsp tho since it's archived now.

[jwong-beep]

Yes, I was thinking more in the line of copy&pasting the generated tsprotocol.go file or the generator itself, with full copyright credits still given to Google of course. The protocol itself only updates once every couple of years, so I think it's probably enough to copy the generated file.

[peterebden]

OK, makes sense!