Update heat and atmosphere in mi-go base

[I-am-Erk]

Summary

SUMMARY: Bugfixes "Adjusts the heat and toxic atmosphere of mi-go bases"

Purpose of change

Fixes #34914

It appears ZhilkinSerg finished jsonizing the heat field code only two weeks after the mi-go base went in, and I was on hiatus at the time and missed it. That's all that's been needed to fix this, so now I'm fixing it.

Describe the solution

Makes a tightly regulated temperature field, hot_air_sauna, that caps off in the high 60 degrees celsius but also has a high bottom end in the 50s - that's what was missing to the hot_air3 field before, it had the capacity to be much too cool. I'll have to test in summer to see how much the outside temperature affects things, but this should keep it uncomfortably hot year round without being completely fatal.

While I was in there, I also changed the concealing clouds of toxic gas in the base to the invisible, smothering atmosphere I'd intended. Instead of being poisonous it makes you tired and less combative. You're forced to choose between further overheating by wearing a gasmask, or being crippled by the toxic air.

Describe alternatives you've considered

I could leave it as is. Surprisingly, the blisteringly hot temperatures in the base didn't have as strong an impact on it as I'd thought: it's getting roughly the play reports I was aiming for, of being nearly impossible to brave, but not entirely. Still, the temperature is definitely not meant to be quite this high, and the fifties to sixties celsius should still be hot enough to seriously deter all but the most well prepared adventurers.

Testing

Temp is a bit low but works. The atmosphere effects don't go in stages as much as I'd like, I may tweak them later, but for now they're working well enough.

[kevingranade]

This pull request has been mentioned on Cataclysm: Dark Days Ahead. There might be relevant details there:

https://discourse.cataclysmdda.org/t/how-to-associate-an-effect-type-with-a-field-type/22018/2