patch 9.0.1804: Vim9: no support for private object methods

Problem:  Vim9: no support for private object methods
Solution: Add support for private object/class methods

closes: #12920

Signed-off-by: Christian Brabandt <cb@256bit.org>
Co-authored-by: Yegappan Lakshmanan <yegappan@yahoo.com>
diff --git a/runtime/doc/todo.txt b/runtime/doc/todo.txt
index 8479e15..6b45aab 100644
--- a/runtime/doc/todo.txt
+++ b/runtime/doc/todo.txt
@@ -129,6 +129,7 @@
 	    or: def _Func()
     Perhaps use "private" keyword instead of "_" prefix?
   - "final" object members - can only be set in the constructor.
+  - Support export/import of classes and interfaces.
   - Cannot use class type of itself in the method (Issue #12369)
   - Cannot use an object method in a lambda  #12417
 	Define all methods before compiling them?