Create a rubocop to ensure policy scopes are applied correctly

If scopes are used in policy files they should meet the following conditions

Scope	Condition
:subject	Block should reference @subject but not @user
:user	Block should reference @user but not @subject
:global	Block should not reference @user or @subject

Scopes can be applied in two ways

with_options scope: :subject, score: 0
condition(:thing_is_enabled) { @subject.thing_is_enabled }

or

condition(:thing_is_enabled, scope: :subject) { @subject.thing_is_enabled }

Additionally, there is an attr_reader for @user and @subject so we should also account for situations where conditions use the attr_reader instead of the instance variables.

For example, this condition uses user which is defined by attr_reader so the cop should fail this example since user is in a condition with a :subject scope.

condition(:thing_is_enabled, scope: :subject) { @subject.thing_is_enabled(user) }