x/tools/gopls: resolve comment links to unimported package-qualified symbols such as [net/http.Request]

[findleyr]

Reported by @mvdan in slack: while the doc comment spec allows for qualified doc links such as [net/http.Request], it looks like the support for these links added in #64648 does not implement this support.

I've run into this as well; we should add this support.

[gabyhelp]

Related Issues and Documentation

• x/tools/gopls: go doc links to symbols in the current package or non-fully-qualified packages do not render as links in tooltips #61677

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[findleyr]

Closing as a dupe of #61677.

[findleyr]

Err, it's not an exact dupe, so I'll track this work separately.

[mvdan]

I ran into this again today. I'd be happy to assist in testing or code review when a fix does come up.

FWIW I see similar issues with e.g. [error] or [error.Error], which do not work as links for https://pkg.go.dev/builtin#error. The builtin package is a bit special and perhaps needs extra code to be handled correctly.