the ability to import dashboards was added in T125644: consolidate graphite metrics monitoring frontends into grafana, what's left is saving remaining dashboards in puppet.
Note that upon migrating a dashboard it is customary to add a top panel indicating the new dashboard URL, e.g. https://grafana.wikimedia.org/dashboard/db/swift redirects users to https://grafana.wikimedia.org/dashboard/file/swift.json