Migrate format definitions to sbom package (#864)

internal/formats/spdx22json/format.go

@@ -1,11 +1,15 @@
 package spdx22json
 
-import "github.com/anchore/syft/syft/format"
+import (
+	"github.com/anchore/syft/syft/sbom"
+)
+
+const ID sbom.FormatID = "spdx-2-json"
 
 // note: this format is LOSSY relative to the syftjson format
-func Format() format.Format {
-	return format.NewFormat(
-		format.SPDXJSONOption,
+func Format() sbom.Format {
+	return sbom.NewFormat(
+		ID,
 		encoder,
 		decoder,
 		validator,