Return verified attestation in verification results (#3212)

This commit modifies the artifact verification results to
also include the verified attestation predicate to the evaluator.

Signed-off-by: Adolfo García Veytia (Puerco) <puerco@stacklok.com>
Co-authored-by: Don Browne <dmjb@users.noreply.github.com>

internal/engine/ingester/artifact/artifact.go

@@ -53,13 +53,19 @@ type Ingest struct {
 }
 
 type verification struct {
-	IsSigned          bool   `json:"is_signed"`
-	IsVerified        bool   `json:"is_verified"`
-	Repository        string `json:"repository"`
-	Branch            string `json:"branch"`
-	SignerIdentity    string `json:"signer_identity"`
-	RunnerEnvironment string `json:"runner_environment"`
-	CertIssuer        string `json:"cert_issuer"`
+	IsSigned          bool                 `json:"is_signed"`
+	IsVerified        bool                 `json:"is_verified"`
+	Repository        string               `json:"repository"`
+	Branch            string               `json:"branch"`
+	SignerIdentity    string               `json:"signer_identity"`
+	RunnerEnvironment string               `json:"runner_environment"`
+	CertIssuer        string               `json:"cert_issuer"`
+	Attestation       *verifiedAttestation `json:"attestation,omitempty"`
+}
+
+type verifiedAttestation struct {
+	PredicateType string `json:"predicate_type,omitempty"`
+	Predicate     any    `json:"predicate,omitempty"`
 }
 
 // NewArtifactDataIngest creates a new artifact rule data ingest engine
@@ -208,6 +214,13 @@ func (i *Ingest) getVerificationResult(
 				verResult.RunnerEnvironment = res.Signature.Certificate.RunnerEnvironment
 				verResult.CertIssuer = res.Signature.Certificate.Issuer
 			}
+
+			if res.Statement != nil {
+				verResult.Attestation = &verifiedAttestation{
+					PredicateType: res.Statement.PredicateType,
+					Predicate:     res.Statement.Predicate,
+				}
+			}
 			// Append the verification result to the list
 			versionResults = append(versionResults, *verResult)
 		}