[draft] Pundit to Action Policy

doc.md

From Pundit to ActionPolicy:

• Remove include Pundit from ApplicationController
• Add alias authorize authorize!
• Add authorize :current_user, as: :user
• Add include ActionPolicy::Policy::Core to ApplicationPolicy
• Update ApplicationPolicy#initialize:

def initialize(target, user:)
  # ...
end

• Add policy helper:

helper_method :policy

def policy(record)
  policy_for(record)
end

NOTE: policy defined above is not equal to allowed_to? since it doesn't take into account pre-checks.

• Replace RSpec helper:

# require 'pundit/rspec'
require 'action_policy/rspec/pundit_syntax'

• TODO: scopes migration

When everything is green, it's time to fully migrate to ActionPolicy:

• make ApplicationPolicy inherit from ActionPolicy::Base
• migrate view helpers (from policy(..) to allowed_to?)
• re-write specs using simple non-DSL syntax
• add controller specs (add require 'action_policy/rspec')