Hoverpod tweaks and mecha/working code cleanup

* Hoverpods are a subtype of ```mecha/working``` again, but mining drills are now ripley specific.
* Hoverpods now have 3 equipment slots and increase cargo capacity.
* When ordered from cargo, hoverpods come with a clamp and passenger compartment pre-installed.
* Refactors a bunch of identical procs shared by hoverpods and ripleys and moves them into ```mecha/working```
* Allows hoverpod stabilization (similar to jetpack stabilzation) to be toggled on or off from the exosuit menu (mostly copied from Phazon UI code).
* Uncomments combatpods, they can now equip weapons.


- [ ] Still needs local testing.
- [ ] Find a better pod sound effect.