Remove code co-sysop flags and exemption checks
I'm unable to make tests work where this code actually performs as expected, where a co-sysop can edit a higher-level sysop only if they have that flag/exemption themselves.
In my opinion:
- The BBS world is past the point of needing this.
- A co-sysop shouldn't be able to add flags/exemptions to a user of any security level if they don't have it themselves.
- A co-sysop shouldn't be able to add flags/exemptions to their own account
But mostly just 1 above. I don't think we need this anymore, and the code should just be simplified to a co-sysop cannot edit a security level above their own, no exceptions.