fix(assets): correct type column in assets (#4295)

* fix(asssets): correct remove asset objects with text column

* fix(assets): type asset_type, correct and add unit tests

* fix(assets): set unspecified objecttype to empty string

Co-authored-by: Livio Spring <livio.a@gmail.com>

internal/static/storage.go

@@ -21,10 +21,21 @@ type Storage interface {
 type ObjectType int32
 
 const (
-	ObjectTypeUserAvatar = iota
+	ObjectTypeUserAvatar ObjectType = iota
 	ObjectTypeStyling
 )
 
+func (o ObjectType) String() string {
+	switch o {
+	case ObjectTypeUserAvatar:
+		return "0"
+	case ObjectTypeStyling:
+		return "1"
+	default:
+		return ""
+	}
+}
+
 type Asset struct {
 	InstanceID    string
 	ResourceOwner string