make HoS non exclusive to mentors

[Firepower]

I don't think it's a lack of HoSs that are preventing security from thriving. Even when I play HoS I rarely get any security officers playing with me. I think the culture at Goonstation makes it sorta difficult to play security and get taken seriously. As sometimes cracking down on people doing "illegal" stuff can be seen as unfun.

Besides I like HoS being a position that is universally identified as trustworthy. If we open it up to anyone then the HoS position will lose its prestige and be about as respected as the captain, which is to say not at all.