AI condensing/rework

[MistakeNot4892]

Description of changes

• Condenses and centralises AI behavior onto /datum/mob_controller, separated by flags rather than types.
• Moves various phases of logic onto /decl/mob_controller_stance.
• Moves various AI commands into /decl/mob_command.
• Unifies business checking and AI activity.

Why and what will this PR improve

Makes much more complex AI behavior available/possible. Not benchmarked. and I don't know if the flag checking offsets any benefits, but should be less overhead in general now without redundant calls to get_target(), stop_automove() etc.

TODO

• Coarse conversion into stance-encapsulated and flag-based system.
• Convert spider behaviors into either commands or a stance/activity.
• Consider /decl/mob_activity to replace activity values/behaviors.
• Formalise state transitions in FSM extension rather than using bespoke logic in /decl/mob_controller_stance.
• Update all flags/configuration on mob AI datums to behave as expected.
• Refine behavior - ranged attackers swapping to melee if forced, avoiding hitting their friends, etc.
• Test all mob commands.
• Test mob fleeing behavior.
• Test mob combat behavior.
• Test spider building and nesting behavior.

Authorship

Myself.

Changelog

🆑
tweak: Massive AI rewrite; keep an eye out for strange behavior from NPCs.
/:cl: