Adding Registry Mirror support

This commit aims to add registy mirror support similar to
docker. The UI is similar to docker where user can
provide mirror urls and the image resolves against the provided
mirrors before fetching from default docker regitry mirror url.

Signed-off-by: abhi <abhi@docker.com>

pkg/server/helpers.go

@@ -210,7 +210,6 @@ func (c *criContainerdService) localResolve(ctx context.Context, refOrID string)
 		if _, err := imagedigest.Parse(refOrID); err == nil {
 			return refOrID
 		}
-
 		return func(ref string) string {
 			// ref is not image id, try to resolve it locally.
 			normalized, err := util.NormalizeImageRef(ref)