feat: add production tuf root

pkg/tuf/tuf.go

@@ -11,6 +11,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/docker/attest/internal/embed"
 	"github.com/docker/attest/internal/util"
 	"github.com/theupdateframework/go-tuf/v2/metadata"
 	"github.com/theupdateframework/go-tuf/v2/metadata/config"
@@ -227,3 +228,8 @@ func ensureTrailingSlash(url string) string {
 	}
 	return url + "/"
 }
+
+// GetEmbeddedTufRootBytes returns the embedded TUF root based on the given root name
+func GetEmbeddedTufRootBytes(root string) ([]byte, error) {
+	return embed.GetRootBytes(root)
+}