Breath code refactoring

[SECBATON-GRIFFON]

[cleanup]

What this does

Makes these files easier to work with, moves relevant code from species into lung gas datums.
Splits off parts of breath() on carbons into separate functions such as check_breath_block() and needs_to_breathe() for modularity and less code reuse.

Why it's good

Easier maintenance for someone who wants to fix or tweak it.

How it was tested

Entering cryotubes, shelters, and wearing a plastic bag on head as a human, calling needs_to_breathe() and check_breath_block() (with a gas mask on) on humans and monkeys, immersing them in a normal room, then opening canisters of plasma and n2o, then spacewalking as each.

Changelog

No user facing changelog.

[Eneocho]

Mr shreshident another refactor has hit the twin repos

[SECBATON-GRIFFON]

Mr shreshident another refactor has hit the twin repos

necessary evil for if someone wants to try the co2 PR again but with fairer balance, or even sanitize lung popping which is my idea going forward.

[Inorien]

pls verify

[Inorien]

also this

[Inorien]

looked at it again

[SECBATON-GRIFFON]

fixed the logic, can't respond to that review for some reason

[Inorien]

gonna be straight with u this is an important refactor that needs to happen but its also very fragile
i really wish i had been looking at it sooner and not just dipping in and out whenever i've had time (i've been sick and busy irl) but i really need to put aside some serious time to look at it in depth given how critical breathing is.

tldr gonna stay unmerged for a bit longer until i scrape together time, hopefully next week some point

[hacker-on-steroids]

kanef PR

not even gonna attempt to review
at least i'll know who's responsible when everything breaks after merge

[13monkeks]

kanef PR

dont even need to read it to updoot
at least i'll know who's responsible when everything becomes objectively better after merge