Add support for multiple output files in different formats (#732)

syft/sbom/writer.go

@@ -0,0 +1,13 @@
+package sbom
+
+import "io"
+
+// Writer an interface to write SBOMs
+type Writer interface {
+	// Write writes the provided SBOM
+	Write(SBOM) error
+
+	// Closer a resource cleanup hook which will be called after SBOM
+	// is written or if an error occurs before Write is called
+	io.Closer
+}