cmd/go: handle queries properly in go install m@v

cmd/go: handle queries properly in go install m@v

The original code only handled go install m@v1.0.0
but not queries like go install m@v1 or m@master.
Handle those by invoking more of the module machinery.

For #57001.

Change-Id: I7d54fc3dd65072e5906a17ff95b407b0f7feac69
Reviewed-on: https://go-review.googlesource.com/c/go/+/497879
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Bryan Mills <bcmills@google.com>
Auto-Submit: Russ Cox <rsc@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>