Color matrix defines for filters and identity (#80320)

This PR converts the procs `color_matrix_identity`,
`color_matrix_lightness` and `color_matrix_contrast` into
defines/macros. Also adds in defines for common color matrix filters.

I don't like how `color_matrix_identity` is a one-line proc with no arg.
Also these help people identify the sort of color matrix filter is being
used.

code/modules/mod/mod_paint.dm

@@ -16,7 +16,7 @@
 
 /obj/item/mod/paint/Initialize(mapload)
 	. = ..()
-	current_color = color_matrix_identity()
+	current_color = COLOR_MATRIX_IDENTITY
 
 /obj/item/mod/paint/examine(mob/user)
 	. = ..()
@@ -66,7 +66,7 @@
 	. = ..()
 	editing_mod = null
 	QDEL_NULL(proxy_view)
-	current_color = color_matrix_identity()
+	current_color = COLOR_MATRIX_IDENTITY
 
 /obj/item/mod/paint/ui_status(mob/user)
 	if(check_menu(editing_mod, user))