Fixes multiple protean issues. (Outfitting, species loss / add, suit assimilation, and you can be a ninja now) (#5947)

## About The Pull Request

Fixes some really long standing Protean issues and minorly refractors
Protean suit assimilation to be on the species datum.

This also fixes antag selection like ninjas not functioning properly.
You can be a protean ninja now.

## Why It's Good For The Game

I think bugs are bad.

## Proof Of Testing

I tested everything I can think of, 

<img width="1199" height="534" alt="image"
src="https://github.com/user-attachments/assets/6906815b-5810-4ec2-bf9a-f928c636b1eb"
/>

## Changelog
🆑
fix: Proteans can now be outfitted properly.
fix: Suit assimilation no longer drops modules on the floor and it
should act more sane.
fix: Losing your species no longer deletes your items in storage or your
assimilated suit.
fix: Gaining the protean species allows you to properly be a Protean.
fix: You can now be mid-round antag spawn as a Protean without being
broken.
fix: As a protean ninja, you can now emag doors and hack borgs.
code: Minorly refactored suit assimilation. Please report any issues.
/🆑

code/modules/admin/verbs/selectequipment.dm

@@ -213,6 +213,8 @@ ADMIN_VERB_ONLY_CONTEXT_MENU(select_equipment, R_FUN, "Select Equipment", mob/ta
 	BLACKBOX_LOG_ADMIN_VERB("Select Equipment")
 	var/includes_flags = delete_pocket ? INCLUDE_POCKETS : NONE
 	for(var/obj/item/item in human_target.get_equipped_items(includes_flags))
+		if(isprotean(human_target) && human_target.get_item_by_slot(ITEM_SLOT_BACK) == item) // BUBBER EDIT
+			continue	// BUBBER EDIT
 		qdel(item)
 
 	var/obj/item/organ/brain/human_brain = human_target.get_organ_slot(BRAIN)