Adds sanitization redundancy for 3-hex colours (#2131)

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## About The Pull Request
Hopefully makes it so that players with three-hex-code colour values
automatically convert to six-hex-code colours.

## Why It's Good For The Game
you don't lose your colours

## Changelog

:cl:
/:cl:

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code/__HELPERS/sanitize_values.dm

@@ -77,6 +77,11 @@
 			i += length(color[i])
 
 	if(length_char(.) != desired_format)
+		if(desired_format == 6 && length_char(.) == 3) //doing this quickly rather than elegantly
+			var/red = .[1]
+			var/green = .[2]
+			var/blue = .[3]
+			return crunch + "[red][red][green][green][blue][blue]"
 		if(default)
 			return default
 		return crunch + repeat_string(desired_format, "0")