cmd/go: add tracing for querying and downloading from the proxy
This CL adds tracing spans for modload.queryPattern, modload.queryProxy,
modload.QueryPattern, modload.QueryPattern.queryModule,
modload.queryPrefixModules and modfetch.Download.
Updates #38714
Change-Id: I91af3f022a6e18ab8d9c1d9b0ccf4928b6c236bd
Reviewed-on: https://go-review.googlesource.com/c/go/+/249022
Run-TryBot: Michael Matloob <matloob@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Jay Conrod <jayconrod@google.com>