Adding GetColor, DrawRectangle, DrawText and GetTextBounds

[brunoluizkatz-NETZSCH]

No description provided.

[gethiox]

there already was AsColor method available on PropertyValue, GetColor could be just:

func GetColor(control ControlID, property PropertyID) rl.Color {
	return GetStyle(control, property).AsColor() 👀 
}

So sad I've missed this PR!
Not worth updating it right away tho, but still a thing to keep in mind for future updates to avoid code duplication.