* add max_exorcism_level to weapons
- migration to add column (nullable integer)
- expose in blueprint
- permit in controller
- add spec for create/update
* default exorcism_level=1 for befoulment weapons
- set default on create for GridWeapon and CollectionWeapon
- data migration to populate existing befoulment weapons
- add specs for default behavior
* add weapon_stat_modifiers table for ax skills and befoulments
* add fk columns for ax modifiers and befoulments, replace has_ax_skills with augment_type
* update models for weapon_stat_modifier fks and befoulments
* update blueprints for weapon_stat_modifier serialization
* update import service for weapon_stat_modifier fks and befoulments
* add weapon_stat_modifiers controller and update params for fks
* update tests and factories for weapon_stat_modifier fks
* fix remaining has_ax_skills and ax_modifier references
* add ax_modifier and befoulment_modifier to eager loading
* fix ax modifier column naming and migration approach
* add game_skill_ids for befoulment modifiers
