Add minetest.get_artificial_light and minetest.get_natural_light (#5680)

Add more detailed light detection functions, a function to get the artificial light (torches) and a function to get the sunlight as seen by the player (you can specify timeofday).

Co-authored-by: rubenwardy <rw@rubenwardy.com>

builtin/game/misc.lua

@@ -151,6 +151,12 @@ function core.setting_get_pos(name)
 end
 
 
+-- See l_env.cpp for the other functions
+function core.get_artificial_light(param1)
+	return math.floor(param1 / 16)
+end
+
+
 -- To be overriden by protection mods
 
 function core.is_protected(pos, name)