Workspace todo and todolist don't have IChanged behavior.

[deiferni]

The changed field and behavior introduced in #4962 should most likely also be enabled for todo and todolist. Currently they are not enabled and were not initially set when todo was implemented in #5808 and todolist in #5829.

So we'd need to do the following:

• add changed behavior to portal types config
• add upgrade to intialize changed on existing content to and set it to modified. Upgrade in Add changed field, metadata and index #4962 can serve as inspiration.