Prefix resource dump filenames with group

Certain api services have conflicting Resource types, causing resource dumps to overwrite eachother.
This ensures filenames remain unique by prefixing them with the api group

pkg/dump/resourcedumper.go

@@ -58,7 +58,13 @@ type gvrNamespace struct {
 }
 
 func (d *gvrNamespace) String() string {
-	return path.Join(d.namespace, d.gvr.Resource)
+	var gr string
+	if d.gvr.Group == "" {
+		gr = d.gvr.Resource
+	} else {
+		gr = fmt.Sprintf("%v.%v", d.gvr.Group, d.gvr.Resource)
+	}
+	return path.Join(d.namespace, gr)
 }
 
 type resourceDumper struct {