Handle errors from Go in Rego. Support for skipping TL (#47)

* Make TL logging/verification optional

* Return errors from go-lang fns

* Update pkg/policy/rego.go

Co-authored-by: Jonny Stoten <jonny@jonnystoten.com>

* Update pkg/attestation/sign.go

Co-authored-by: Joel Kamp <joel.kamp@docker.com>

* Move public key marshelling until later

* Simplify logSignature and pass down opts

---------

Co-authored-by: Jonny Stoten <jonny@jonnystoten.com>
Co-authored-by: Joel Kamp <joel.kamp@docker.com>

pkg/attestation/types.go

@@ -66,6 +66,17 @@ type DockerTlExtension struct {
 	Data any    `json:"data"`
 }
 
+type VerifyOptions struct {
+	Keys   []KeyMetadata `json:"keys"`
+	SkipTL bool          `json:"skip_tl"`
+}
+
+type SigningOptions struct {
+	Replace     bool
+	SkipTL      bool
+	PayloadType string
+}
+
 func DSSEMediaType(predicateType string) (string, error) {
 	var predicateName string
 	switch predicateType {