Gibs you leave are now based on your biotype/chest bodypart, improves gibber VFX (#91421)

## About The Pull Request

* When gibbing mobs, spawned gib type is now based on mob's biotypes if
they're not a carbon, or their chest (or first) bodypart if they are,
rather than requiring a proc override for every single mob. This means
that a few robotic mobs no longer drop meaty gibs, and that gibbing
androids now produces cyborg gibs instead of a meaty surprise, plus they
should no longer runtime when trying to gib a robot. Gibs also are now
spawned around the gibber and streak outwards instead of magically
teleporting a few tiles away, for some visual flair.
* Fixed meat not overriding blood DNA on blood_walk component which made
xeno and lizard meat leave behind orange trails instead of proper
lime/dark green blood colors (due to them keeping human meat DNA).
* Brightened up the gibber blood overlay I've missed, so it should be
consistent with old blood colors now.
* Also cleaned up the gibspawner code.

## Why It's Good For The Game

Biotype/chest changes should make devs lives easier and gameplay a bit
more consistent, and streaking just makes the process look slightly
better.

## Changelog
🆑
add: Androids and fully augmented humans now drop robotic gibs instead
of meat
add: Improved gibber VFX
fix: Fixed gibber overlays being darker than intended
fix: Fixed xenomorph and lizard meat leaving orange trails behind
code: Improved gibs and gibspawner code
/🆑

code/modules/spells/spell_types/shapeshift/_shapeshift.dm

@@ -121,7 +121,7 @@
 		our_pipeline = pipenets
 
 	to_chat(cast_on, span_userdanger("Casting [src] inside of [pipe_you_die_in] quickly turns you into a bloody mush!"))
-	var/obj/effect/gib_type = isalien(cast_on) ? /obj/effect/gibspawner/xeno : /obj/effect/gibspawner/generic
+	var/obj/effect/gib_type = cast_on.get_gibs_type()
 
 	for(var/obj/machinery/atmospherics/components/unary/possible_vent in range(10, get_turf(cast_on)))
 		if(length(possible_vent.parents) && possible_vent.parents[1] == our_pipeline)