Support for LSP's Show Document Request

[ashishbhate]

tl;dr: Please consider adding support for LSP's Show Document Request capability.

The language support protocol added "Show Document Request" in version 3.16.0 of the protocol.

Golang's language server gopls uses this ability to tell the client to show package documentation and to browse the compiler generated assembly (amongst other things)
See: https://github.com/golang/tools/blob/master/gopls/doc/features/web.md

When the client (in this case, zed) does not support "Show Document Request", gopls falls back to using LSP's showMessage ability (which zed does support)
See: https://github.com/golang/tools/blob/c0dbb60e4ba78287d76e623a94ae61616ff3c74c/gopls/internal/server/command.go#L1547-L1564

The problem with this is that zed shows the message from showMessage as plain text in a dialog at the bottom right of the window.

This text is not clickable, so I need to copy it by clicking the copy button at the top right of that dialog, then paste the text in the browser URL, and remove the leading "Doc: open your browser to" part because the copy button copies the whole text. This is a bit annoying :)

VSCode implements the Show Document Request capability and directly opens a tab the default browser. It would be great if zed could do this as well.

I searched the zed issue's tracker and found #17931
This issue is partially related. The OP in that ticket reported that "nothing happens" because when that ticket was opened zed didn't advertise LSP's showMessage capability. Advertising the showMessage capability was only added a few months ago - #21924