ColorRect & CanvasModulate Icons reflect their inspector set color

[bergiebird]

The current Icons would stay as is in the Create New Node but their internal rainbow image would update to white, their starting colors, when they first enter the Scene Tree. The external green or blue rectangles would stay as is for clarity.

The icon in the Scene Tree would auto update based on the user selected color in the inspector.

This feature would be disabled when Remote.

Could be a fun visual change to the editor and give each SceneTree a more unique quality.