Salvage / Borg Tweaks (#2145)

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# Description

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Originally started because I wanted to add some stuff to salvage, but
ended up with me porting over whitelisted borg hands, the PKA module,
and some other stuff.

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# Changelog

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🆑
- add: Engi borgs can now carry electronics, and medical borgs can carry
organs
- add: Salvage borgs now get a PKA module
- tweak: All mining drills have had their damage turned to piercing and
have received a moderate damage buff
- tweak: Exosuit drills now swing at the same speed as normal drills
(why were they worse???)
- tweak: The RPD and RCD modules for borg have been merged into one
- tweak: Salvage can now purchase drills from their vendor
- tweak: Salvage borgs mining module no longer contains a shovel

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Co-authored-by: Your Name <EctoplasmIsGood@users.noreply.github.com>
Co-authored-by: Whatstone <whatston3@gmail.com>
Co-authored-by: RatherUncreative <RatherUncreativeName@proton.me>
Co-authored-by: Aidenkrz <aiden@djkraz.com>
(cherry picked from commit ed8850e551bd9c0d533d69cad262a8743442a62a)

Content.Server/Stack/StackSystem.cs

@@ -51,7 +51,7 @@ namespace Content.Server.Stack
 
             // Get a prototype ID to spawn the new entity. Null is also valid, although it should rarely be picked...
             var prototype = _prototypeManager.TryIndex<StackPrototype>(stack.StackTypeId, out var stackType)
-                ? stackType.Spawn
+                ? stackType.Spawn.ToString()
                 : Prototype(uid)?.ID;
 
             // Set the output parameter in the event instance to the newly split stack.