Refactor minds, antag spawning and enslave_to_creator

[PowerfulBacon]

enslave_to_creator is a proc that does a lot of specific behaviour, and once a mob is enslaved they won't inherit antag datums that their owner obtain which is confusing.

I propose the following refactor:

• Seperate equipping antags from applying an antag datum so that antags can be applied without specific overrides to disable equipping for each antag
• Upon being enslaved, register a signal to the owner mind and inherit their antags
• Upon being enslaved, lose all antag datums
• Upon being enslaved, join all owner antag datum's teams.