added firebase and rudimentary leaderboard support

addons/godot-firebase/firestore/field_transform.gd

@@ -0,0 +1,22 @@
+extends FirestoreTransform
+class_name FieldTransform
+
+enum TransformType { SetToServerValue, Maximum, Minimum, Increment, AppendMissingElements, RemoveAllFromArray }
+
+const transtype_string_map = {
+	TransformType.SetToServerValue : "setToServerValue",
+	TransformType.Increment : "increment",
+	TransformType.Maximum : "maximum",
+	TransformType.Minimum : "minimum",
+	TransformType.AppendMissingElements : "appendMissingElements",
+	TransformType.RemoveAllFromArray : "removeAllFromArray"
+}
+
+var document_exists : bool
+var document_name : String
+var field_path : String
+var transform_type : TransformType
+var value : Variant
+
+func get_transform_type() -> String:
+	return transtype_string_map[transform_type]