aboveEditable renders should only wrap the editable area

[mattiaz9]

Right now if a plugin renders a beforeEditable, such the toolbar, when another plugin is rendered using aboveEditable it also wraps the siblings components.
This is, in my opinion, wrong because It makes very difficult to implement a custom layout. It also creates some unwanted behaviors, such as the contextual menu that appears outside the editable area.
Also, there is already aboveSlate that should wrap the entire content if needed, so I don't see why having the same behavior for the aboveEditable.

I believe you should change the behavior of the aboveEditable to only wrap the slate editable area.

[zbeyens]

This makes sense, PR's appreciated.

[mattiaz9]

here you go! #4182