Drones releasing from ssu

Added the ability for drones to get out of suit storage units with the unit controls, fixing Issue #4904 . They were able to do this before by typing resist, but this adds a visual option.
This is my first pull request, so please tell me if I'm doing something / anything wrong!
Checking for type like this is considered poor form; it makes the code messier and causes issues down the line. If another mob like drones were added for example then you'd need to make another exception, etc.