True controlled behavior for Editable

[brunobely]

Currently, the Editable component isn't truly controllable - that is, even if you pass it a value, that value only affects the preview, not the underlying input. This breaks functionality where you'd need a true controlled component, like preventing certain characters from being entered or formatting the user's input on paste.

I'm not sure what the fix is, but it would be nice if the component could support being controlled!