Include image name in archive zip filename

[jgallagher]

This makes three changes, two of which only affect CI (and any following scripts / processes that use CI artifacts):

1. (Affects everyone) Hubris archive names now have a suffix of -image-X, where X is "default" for most images. E.g., what was once build-psc-c.zip is now build-psc-c-image-default.zip. This matters most for the RoT images; what was once build-gimlet-rot-c.zip (and you had to know what directory it was in and/or inspect its contents to tell if it was an A or B image) is now build-gimlet-rot-c-image-a.zip.
2. The CI artifacts for the RoT builds now contain both A and B hubris archives.
3. We no longer upload the artifacts built by the Windows runner (but we do still run the builds on Windows). Since we were cross compiling, I believe (?) these should've been identical, and I don't think anyone was using them.

[steveklabnik]

I believe (?) these should've been identical, and I don't think anyone was using them.

Yep!