Carbon monoxide should probably work differently

Description of issue

Carbon monoxide currently causes you to physically, mechanically stop breathing, because it is renamed Baystation lexorin (I think that was the name?). This isn't what carbon monoxide does, and also means it's really punishing on low-tech maps where fire sources are used, because there aren't any treatment options to reverse it. It also scales really strongly with mob size currently (but there's two PRs up to fix that issue).

We should probably change how it works, and make a different chemical have the lexorin-style effect (increment suffocation_counter) instead.

Difference between expected and actual behavior

Carbon monoxide should probably just act as inverse-oxymeds, where it lowers your blood oxygenation level (maybe negative CE_OXYGENATION or something?).

Steps to reproduce

N/A

Specific information for locating

N/A

Length of time in which bug has been known to occur

Since it was renamed from lexorin to carbon monoxide

Client version, Server revision & Game ID

N/A

Issue bingo

• Issue could be reproduced at least once
• Issue could be reproduced by different players
• Issue could be reproduced in multiple rounds
• Issue happened in a recent (less than 7 days ago) round
• Couldn't find an existing issue about this

No file, test, or entry point is named. Start by locating the carbon monoxide and oxymed chemical implementations, then inspect how suffocation_counter and CE_OXYGENATION are handled; done requires agreeing on the intended chemical effect and adding a replacement for the current lexorin-style behavior.