Add a unit test to check that maploaded simple/basic mobs are in an environment they can survive in. (#82180)

## About The Pull Request
I've recently noticed that the maploaded penguins from the snowdin away
mission were dying from unsafe atmos/temperature. This sparked the idea
of making a (focus only) unit test that would prevent this sort of
issues from happening.

This PR also implements the usage of the `atmos_requirements` and
`body_temp_sensitive` elements for simple animals too, cutting down the
copypaste.

## Why It's Good For The Game
More unit tests to make sure things are done correctly.

## Changelog

🆑
fix: Made sure that mapped critters (i.e. penguins on the snow cabin
away mission) can survive in the environment they're spawned in.
/🆑

code/modules/mob/living/basic/pets/dog/dog_subtypes.dm

@@ -38,6 +38,13 @@
 	collar_icon_state = "bullterrier"
 	held_state = "bullterrier"
 
+/mob/living/basic/pet/dog/bullterrier/lavaland_party
+	name = "Saint Nick's Helpful Associate"
+	desc = "Undergraduate in 'Being a Good Boy'."
+	habitable_atmos = null
+	gold_core_spawnable = NO_SPAWN
+	unique_pet = TRUE
+
 /mob/living/basic/pet/dog/breaddog //Most of the code originates from Cak
 	name = "Kobun"
 	real_name = "Kobun"

code/modules/mob/living/basic/pets/fox.dm

@@ -72,3 +72,10 @@
 // A more docile subtype that won't attack other animals.
 /mob/living/basic/pet/fox/docile
 	ai_controller = /datum/ai_controller/basic_controller/fox/docile
+
+/mob/living/basic/pet/fox/icemoon
+	name = "icemoon fox"
+	desc = "A fox, scraping by the icemoon hostile atmosphere."
+	gold_core_spawnable = NO_SPAWN
+	habitable_atmos = null
+	minimum_survivable_temperature = ICEBOX_MIN_TEMPERATURE

code/modules/mob/living/basic/pets/orbie/orbie.dm

@@ -13,7 +13,7 @@
 	light_range = 6
 	light_color = "#64bee1"
 	health = 100
-	habitable_atmos = list("min_oxy" = 0, "max_oxy" = 0, "min_plas" = 0, "max_plas" = 0, "min_co2" = 0, "max_co2" = 0, "min_n2" = 0, "max_n2" = 0)
+	habitable_atmos = null
 	unsuitable_atmos_damage = 0
 	can_buckle_to = FALSE
 	density = FALSE

code/modules/mob/living/basic/pets/penguin.dm

@@ -196,4 +196,10 @@
 /mob/living/basic/pet/penguin/baby/permanent
 	can_grow_up = FALSE
 
+/mob/living/basic/pet/penguin/emperor/snowdin
+	minimum_survivable_temperature = ICEBOX_MIN_TEMPERATURE
+	gold_core_spawnable = NO_SPAWN
 
+/mob/living/basic/pet/penguin/baby/permanent/snowdin
+	minimum_survivable_temperature = ICEBOX_MIN_TEMPERATURE
+	gold_core_spawnable = NO_SPAWN