Add transformer for container roots

This change renames the root transformer to indicate that it
operates on host paths and adds a container root transformer for
explicitly transforming container roots.

The transform.NewRootTransformer constructor still exists, but has
been marked as deprecated.

Signed-off-by: Evan Lezar <elezar@nvidia.com>

cmd/nvidia-ctk/cdi/transform/root/root.go

@@ -104,7 +104,7 @@ func (m command) run(c *cli.Context, opts *options) error {
 		return fmt.Errorf("failed to load CDI specification: %w", err)
 	}
 
-	err = transform.NewRootTransformer(
+	err = transform.NewHostRootTransformer(
 		opts.from,
 		opts.to,
 	).Transform(spec.Raw())