Allow wysiwyg widgets without admin widget modals

[vestimir]

Widgets that can be edited without opening the widget settings modal, for example rich-markdown-editor.

Use case:

A widget that doesn't have an admin modal, when a user is logged he can manipulate the widget settings directly. Once a change is made the save of a widget is to be triggered.

Variants:

• AdminWidget context
• onChange callback on the widget itself as a prop