Return the underlying images metadata

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

image.go

@@ -58,6 +58,8 @@ type Image interface {
 	IsUnpacked(context.Context, string) (bool, error)
 	// ContentStore provides a content store which contains image blob data
 	ContentStore() content.Store
+	// Metadata returns the underlying image metadata
+	Metadata() images.Image
 }
 
 type usageOptions struct {
@@ -130,6 +132,10 @@ type image struct {
 	platform platforms.MatchComparer
 }
 
+func (i *image) Metadata() images.Image {
+	return i.i
+}
+
 func (i *image) Name() string {
 	return i.i.Name
 }