changes blood_absorption_rate into proc/get_blood_absorption_rate() and make it depend on the blood level on living/human

[M-Earthfire]

[medical][rework][internal]

About the PR

This PR removes blood_absorption_rate from /mob/living and instead introduces /mob/living/proc/get_blood_absorption_rate(). This proc returns a value that is instead of blood_absorption_rate used to determine how much blood a target gains from blood in their reagent holder.

Secondly, for living/human, the blood absorption rate now depends on how high their blood level is. On hypotension it is higher, on hypertension lower.

At following blood levels, blood will be metabolized at the following rates (formerly 1u/lifetick)

• 551+ : 0,8u/lifetick
• 476 - 550: 1u/lifetick
• 426 - 475: 1.25u/lifetick
• 301 - 425: 1.5u/lifetick
• 201 - 300: 2u/lifetick
• 0 - 299: 3u/lifetick

Why's this needed?

Firstly, this enables to set the blood absorption rate dynamically depending on the circumstances on the mob. This means e.g. we could make mutantraces that have a much harder time absorbing blood. Or add mutations that inhibit the absorption of blood or make it easier to bloodgib.

Secondly, Making the blood absorption rate depend on the blood level on humans makes it easier to treat severe cases of hypotension (e.g. vampire attacks). Likewise, it makes blood injection to bloodgib slightly harder.

Lastly, it wa brought to my attention that the dialysis machine buff in #16698 made it able to overpower the blood metabolism rate and, given unreasonable long use, bleed people dry. With this change, the blood level will reach an equilibrium at around 430 blood level.

Changelog

(u)Lord_Earthfire
(+)Being hypotensive makes it easier to receive blood via injetions (e.g. bloodbags) and likewise being hypertensive causes injected blood to be slightly harder to metabolize