[MIRROR] Color standardization, vars moved, and signals (#194)

* Color standardization, vars moved, and signals (#52574)

    Defined all the existing light_color values.
    Moved their definitions to colors.dm
    Made white the default color. It was so already, but that was very obscured.
    Moved the atom light-related variables to the atom definition.
    Wrapped changes to variables such as light_color into procs that report the event through signals.
    Moved the light_on variable to the atom level, also adding a signal for its changing, to represent toggling lights.
    Cleaned up a little bit of code in where new variables were defined before redefinitions.

This is all atomization to reduce changes in #52413
None of this affect gameplay at all, it's all code cleaning and refactoring.

There's more colors to standardize, a search for color = will find lots of targets, and I see little need to have both the LIGHT_COLOR and COLOR patterns, but I don't want to make this PR bigger than it already is.

* Color standardization, vars moved, and signals

Co-authored-by: Rohesie <rohesie@gmail.com>

code/game/objects/structures/flora.dm

@@ -371,7 +371,7 @@
 	name = "photosynthetic potted plant"
 	desc = "A bioluminescent plant."
 	icon_state = "plant-09"
-	light_color = "#2cb2e8"
+	light_color = COLOR_BRIGHT_BLUE
 	light_range = 3
 
 /obj/item/kirbyplants/fullysynthetic

code/game/objects/structures/icemoon/cave_entrance.dm

@@ -76,7 +76,7 @@ GLOBAL_LIST_INIT(ore_probability, list(/obj/item/stack/ore/uranium = 50,
 	icon_state = "nether"
 	mob_types = list(/mob/living/simple_animal/hostile/asteroid/ice_demon)
 	light_range = 1
-	light_color = LIGHT_COLOR_RED
+	light_color = COLOR_SOFT_RED
 
 /obj/structure/spawner/ice_moon/demonic_portal/clear_rock()
 	for(var/turf/F in RANGE_TURFS(3, src))