Support go get/go import redirects

For instance: `golang.org/x/text` is effectively from a git repo at git https://go.googlesource.com/text

The URL at https://golang.org/x/text serves this:

```HTML

The Go Programming Language

Redirecting to documentation...

```

And `go.roman.zone/go-get-redirect` is serving this redirect:
```HTML

See https://pkg.go.dev/go.roman.zone/go-get-redirect for documentation.

window.location = "https://pkg.go.dev/go.roman.zone/go-get-redirect"

```

See also:
- https://github.com/bombsimon/meta-go-imports
- https://pkg.go.dev/cmd/go#hdr-Remote_import_paths