Provide a way to display a warning message before Live Data inline editing

Currently, when an Live Data property can be edited, we can't display a contextual warning message.
This can be dangerous in some context where the editable data can have bad consequences (for instance, changing the owner of a subwiki can lock current user out).
To prevent this kind of issues we often introduce a warning message, explaining the user why and how editing the value can be dangerous.

To mitigate this, we should integrate such warning messages in the LD inline editing workflow.