feat(image): save layers metadata into report (#8394)

Co-authored-by: knqyf263 <knqyf263@gmail.com>

integration/integration_test.go

@@ -153,6 +153,9 @@ func readReport(t *testing.T, filePath string) types.Report {
 	// We don't compare repo tags because the archive doesn't support it
 	report.Metadata.RepoTags = nil
 	report.Metadata.RepoDigests = nil
+	for i := range report.Metadata.Layers {
+		report.Metadata.Layers[i].Digest = ""
+	}
 
 	for i, result := range report.Results {
 		for j := range result.Vulnerabilities {