This change introduces various improvements surrounding deployment
images that are downloaded rather than built locally.
Default images for Centos 8/9 Stream, Ubuntu 20.04/22.04, and Rocky
Linux 8/9 have all been added. These can be selected by setting
upstream_deploy_image_distribution and upstream_deploy_image_release,
and are deployed when download_custom_deploy_image is true.
The deployment image will not be re-downloaded if it already exists, and
its checksum matches
Change-Id: Ib0a1dac2bd0c4c3cf721bcf3042dbd34e2ab2dbd
ba394546e2