cmd/go: extract module zip files in place

Previously, we extracted module zip files to temporary directories
with random names, then renamed them to their final locations. This
failed with ERROR_ACCESS_DENIED on Windows if any file in the
temporary was open. Antivirus programs did this occasionally. Retrying
the rename did not work (CL 220978).

With this change, we extract module zip files in place. We create a
.partial file alongside the .lock file to indicate a directory is not
fully populated, and we delete this at the end of the process.

Updates #36568

Change-Id: I75c09df879a602841f3459322c021896292b2fdb
Reviewed-on: https://go-review.googlesource.com/c/go/+/221157


Run-TryBot: Jay Conrod <jayconrod@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
Reviewed-by: Michael Matloob <matloob@golang.org>