Prevent bioscrambling from/into unremovable/hidden organs or limbs (#5291)

## About The Pull Request

This prevents limbs with `BODYPART_UNREMOVABLE`, or organs with
`ORGAN_UNREMOVABLE` or `ORGAN_HIDDEN` from being bioscrambled into
something else, and also makes any limbs/organs with those flags
ineligible to be picked to bioscramble something _into_.

Was originally a part of
#5290, but I
atomized it into its own PR.

Unsure if this QoL, balance, or perhaps a fix. Gonna mark it as QoL for
now.

## Why It's Good For The Game

prevents weird jank that wouldn't really otherwise be possible, and can
cause problems:tm: with weird edge-cases and such

## Changelog
:cl:
qol: Unremovable or hidden organs/limbs will no longer be bioscrambled,
and are also no longer eligible bioscrambler results.
/:cl:

Author: Absolucy

code/modules/mob/living/carbon/carbon_defense.dm

@@ -837,14 +837,14 @@
 	var/changed_something = FALSE
 	var/obj/item/organ/new_organ = pick(GLOB.bioscrambler_valid_organs)
 	var/obj/item/organ/replaced = get_organ_slot(initial(new_organ.slot))
-	if (!(replaced?.organ_flags & ORGAN_SYNTHETIC))
+	if (!(replaced?.organ_flags & (ORGAN_SYNTHETIC | ORGAN_UNREMOVABLE | ORGAN_HIDDEN))) // monkestation edit: also check ORGAN_UNREMOVABLE and ORGAN_HIDDEN
 		changed_something = TRUE
 		new_organ = new new_organ()
 		new_organ.replace_into(src)
 
 	var/obj/item/bodypart/new_part = pick(GLOB.bioscrambler_valid_parts)
 	var/obj/item/bodypart/picked_user_part = get_bodypart(initial(new_part.body_zone))
-	if (!(picked_user_part?.bodytype & BODYTYPE_ROBOTIC))
+	if (!(picked_user_part?.bodytype & BODYTYPE_ROBOTIC) || (picked_user_part?.bodypart_flags & BODYPART_UNREMOVABLE)) // monkestation edit: check BODYPART_UNREMOVABLE
 		changed_something = TRUE
 		new_part = new new_part()
 		new_part.replace_limb(src, special = TRUE)
@@ -862,14 +862,14 @@
 /mob/living/carbon/proc/init_bioscrambler_lists()
 	var/list/body_parts = typesof(/obj/item/bodypart/chest) + typesof(/obj/item/bodypart/head) + subtypesof(/obj/item/bodypart/arm) + subtypesof(/obj/item/bodypart/leg)
 	for (var/obj/item/bodypart/part as anything in body_parts)
-		if(!is_type_in_typecache(part, GLOB.bioscrambler_parts_blacklist) && !(part::bodytype & BODYTYPE_ROBOTIC) && !(part::limb_id in GLOB.bioscrambler_limb_id_blacklist))
+		if(!is_type_in_typecache(part, GLOB.bioscrambler_parts_blacklist) && !(part::bodytype & BODYTYPE_ROBOTIC) && !(part::bodypart_flags & BODYPART_UNREMOVABLE) && !(part::limb_id in GLOB.bioscrambler_limb_id_blacklist)) // monkestation edit: check BODYPART_UNREMOVABLE
 			continue
 		body_parts -= part
 	GLOB.bioscrambler_valid_parts = body_parts
 
 	var/list/organs = subtypesof(/obj/item/organ/internal) + subtypesof(/obj/item/organ/external)
 	for (var/obj/item/organ/organ_type as anything in organs)
-		if(!is_type_in_typecache(organ_type, GLOB.bioscrambler_organs_blacklist) && !(organ_type::organ_flags & ORGAN_SYNTHETIC) && organ_type::zone != "abstract")
+		if(!is_type_in_typecache(organ_type, GLOB.bioscrambler_organs_blacklist) && !(organ_type::organ_flags & (ORGAN_SYNTHETIC | ORGAN_UNREMOVABLE | ORGAN_HIDDEN)) && organ_type::zone != "abstract") // monkestation edit: also check ORGAN_UNREMOVABLE and ORGAN_HIDDEN
 			continue
 		organs -= organ_type
 	GLOB.bioscrambler_valid_organs = organs