Support providing a callback class to after_* methods in ActiveRecord

[tmcw]

ActiveRecord supports providing a class as the argument to a callback: https://guides.rubyonrails.org/active_record_callbacks.html#callback-classes

class PictureFile < ApplicationRecord
  after_destroy PictureFileCallbacks
end

But the types for ActiveRecord classes only allow a nilable Symbol as the first argument to callbacks:

sorbet-typed/lib/activerecord/all/activerecord.rbi

Line 1070 in 9298edd

arg: T.nilable(Symbol),

[jez]

https://sorbet.org/docs/faq#it-looks-like-sorbets-types-for-the-stdlib-are-wrong