Extract common artifacts across all projects into separate section in bundle

The bundle manifest has contains the artifacts for all projects we build and vend as part of EKS-A and required to bootstrap an EKS-A cluster. Currently there are as many "versioned bundles" in the manifest as the Kubernetes versions we support, courtesy EKS Distro. But the only artifacts that change across these bundles are the EKS-Distro-specific artifacts, like Kind, OVA/Raw images, cloud-provider-vsphere, etc., while the images and S3 artifacts for the rest of the projects are the same but repeated across every bundle. This redundancy increases the size of the bundle and makes it hard to parse and peruse. We can greatly condense the size of the bundle by extracting the common artifacts into a `Shared` section and separating out only the Kubernetes version-specific artifacts like we do today.