Use CSS to create select tool rectangular preview

[zeyadhazem]

Currently the rectangle created on select tool is a temporary pixel.js rectangle object. Drawing such a rectangle requires the layer's canvas to be refreshed every time the rectangle is being resized. This results in a slowly responsive selection. Using CSS will avoid this behaviour specially since there is no need for canvas refresh.

[zeyadhazem]

Creating a square when pressing shift will also be another challenge