Allow Security Assistants to roll antag roles.

[Lefinch]

We already have enough of a polite and civil discourse every few months about the detective and their antag status, mindshields and putting them on or off secassistants/detectives, and the multiform complex impacts this has on the security environment so I openly admit my current objections to the idea get as far as thinking of how much a lit fuse this would be to security dynamics before waving the idea off even though I actually somewhat agree with the "Everyone could be a threat" concept, I end up thinking "is this going to make security have to second guess if a security assistant is just relatively new or being evil or just terrible" or "Will it influence officers in training new assistants in a way that sucks" and while I hope not, the idea is sad enough to make me think twice on this one even if yeah, I think enemies within can be fun.

And they still can be with a bit of effort, mindhack (which works on assistants) or cheeky consumption by the changeling. We now have some more potential for it (and even officers and the HoS) in the Broken on Neon, so maybe that'll go well enough to suggest this might actually work out okay but right now I'm pretty leery about it.