Hide SelectEffect when editing the CanvasItem model properties

[Alecaddd]

Expected Behavior

When the user edits the properties of a CanvasItem the SelectEffect should disappear until the end of the interaction, with a delay of 2 seconds.

This behaviour is commonly used in other design tools to remove the visual noise of the selection bound when the user needs to edit the visual aspects of an item.

Eg. editing the color of a 1px thick border is pretty hard with the selection bound border in the way.

Current Behavior

The selection effect is always visible.

Possible Solution

We should emit a signal whenever a property we know can benefit from not having the selection visible is getting edited by the user.
The SelectedBoundManager can then hide itself and set a delay of 2 seconds before turning back visible.

I'm suggesting the use of a delay to avoid visual glitches when quickly editing a property. eg. typing the color or the opacity value.

[Alecaddd]

This will also help us to solve the problem of updating the selection bounds when the border thickness changes.