Add GetPixel() for Icon

[Sorrowfulwinds]

Adds proc/GetPixel(x, y, icon_state, dir = 0, frame = 0, moving = -1) for #2194.

It has 2 TODOs that cannot be implemented currently:
-The moving var does nothing as OD does not currently track that variable from DMI's
-If icon_state is not in the icon BYOND will either pull the empty string/null icon_state by default or if one does not exist it will pull the first icon_state in the dmi. OD does not track this so it only defaults to checking for an empty string state before failing.

Vars:
X&Y - Must be >1 and less than the max dimension +1 of the icon_state.
icon_state - Must be a string.
dir - Must be a valid integer of dirs N E S W NE NW SE SW (1,2,4,5,6,8,9,10) or 0. 0 counts as South.
frame - Values less than 1 count as 1. Must be less than the total frames +1 of the icon_state.
moving - not implemented

[wixoaGit]

Using DreamIcon.States is going to get you the textures before any sort of modifications like /icon.Blend() are applied. You need to use the result of iconObj.GenerateDMI() to get the final DMI.

[wixoaGit]

You can cast the value instead of having a switch

Suggested change

	AtomDirection atomDir = dir switch {
	0 or 2 => AtomDirection.South,
	1 => AtomDirection.North,
	4 => AtomDirection.East,
	5 => AtomDirection.Northeast,
	6 => AtomDirection.Southeast,
	8 => AtomDirection.West,
	9 => AtomDirection.Northwest,
	10 => AtomDirection.Southwest,
	_ => AtomDirection.None
	};
	//BYONDISM: Bad dir values just crash instantly :)
	if (atomDir == AtomDirection.None) return DreamValue.Null;
	//BYONDISM: Bad dir values just crash instantly :)
	if (!Enum.IsDefined(typeof(AtomDirection), dir)) return DreamValue.Null;
	var atomDir = (AtomDirection)dir;