Upload artifacts from all legs and publish them Arcade-style

[crummel]

This allows us to collect all RID-specific packages as well as conforming to Arcade-style builds and cleaning up our publishing.

[dagood]

Quick note: I think this should include publishing the tarballs Arcade-style.

Maybe there's a way to get involved in some process that moves them automatically to the public on release day, so we can include them in the release notes? Maybe wishful thinking. In any case, having arcade-style publishing is a good place to start here, and if there's no ->public automation, we can have a release-day rebuild that produce and publishes tarballs arcade-style so we can at least link those into the release.