Provide release artifacts necessary to perform bootstrap build offline

Today, all artifacts needed to perform a bootstrap build are retrieved via running `prep.sh`. This script provides options to control which artifacts are retrieved. The intend is that if you want to build, you acquire the source via a source-tarball or cloning the git repo. To build offline you then must run prep.sh. This workflow is not compatible with the way distro maintainers commonly need to build. They need the ability to acquire the source/artifacts necessary to build and then feed them into their build systems. Running a separate step locally is inconvenient. Furthermore, the prep.sh script doesn't make it easy to grab the various artifacts/prereqs it retrieves/downloads that would then need to be fed into the build systems.

To better support distro maintainers, we should be attaching the various artifacts/prereqs to our releases. For items like the bootstrap sdk, a link could be provided. Distro maintainers can then more easily see what is needed to build, can retrieve them, validate via signatures/checksums, and then feed them into their build systems.