More granular Atlas logs & Holomap Init Tweaks (#4056)

changes:

Atlas now logs init time per DMM.
Map Finalization now separately logs finalize & asteroid generation time.
Added Z_ALL_TURFS() macro to get a list of all turfs in a Z-level.
Misc. performance optimizations for SSminimap init.

code/controllers/subsystems/initialization/map_finalization.dm

@@ -9,10 +9,14 @@
 	// Setup the global antag uplink. This needs to be done after SSatlas as it requires current_map.
 	global.uplink = new
 
+	var/time = world.time
 	current_map.finalize_load()
+	log_ss("map_finalization", "Finalized map in [(world.time - time)/10] seconds.")
 
 	if(config.generate_asteroid)
+		time = world.time
 		current_map.generate_asteroid()
+		log_ss("map_finalization", "Generated asteroid in [(world.time - time)/10] seconds.")
 
 	// Generate the area list.
 	resort_all_areas()