Add an icon to the docked panel

[gikari]

Currently MCP Pro tab does not have an icon.

It would be nice it to have one.

To display the icons in the docks at the bottom, this setting must be enabled:

I believe the icon could be set by using EditorDock class:

	dock = EditorDock.new()
	dock.title = "MCP Pro"
	dock.dock_icon = preload("uid://...")