[Feature]: Detect when Antistasi mod isn't loaded

[jaj22]

If the server is localhost, or has verifySignatures disabled, or Antistasi loaded with -servermod, it's possible for a client to connect without loading the Antistasi mod. They see the HQ objects and may be able to interact with some of them, but they don't get most actions or the status bar.

Because Antistasi still runs a mission, it's possible to detect this case in initPlayerLocal and warn the player that they're not running the mod.