Fix collection weapon awakening_level errors

[jedmund]

Summary

• Fix awakening_level null errors when editing collection weapons (both "not included in the list" and PG::NotNullViolation)
• Add before_validation callback to reset awakening_level to 1 when awakening is cleared, on both CollectionWeapon and GridWeapon
• Add descriptive validation messages to CollectionWeapon inclusion validators
• Tests for the callback behavior and validation messages

Test plan

• bundle exec rspec spec/models/collection_weapon_spec.rb spec/models/grid_weapon_spec.rb
• Edit a collection weapon with an awakening-capable series, change only uncap level — should succeed