Add Release String Parsing to fwget

In order to generate our google storage file paths, we'll need to be
able to break down a release string. This change adds that
functionality.

BUG=b:266093164
TEST=manual and unit tests (go test./...)

Change-Id: Id3f72a701e2b4138d6335634328d3dc10e207922
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crostestutils/+/4219877
Reviewed-by: Kevin Shelton <kmshelton@chromium.org>
Tested-by: Sean Carpenter <seancarpenter@google.com>
Commit-Queue: Sean Carpenter <seancarpenter@google.com>
2 files changed