Add array and hash literal offenders to AttributeDefaultBlockValue

[cilim]

The Attributes API also allows defining attributes that are arrays or hashes.

#   # bad
#   class User < ApplicationRecord
#     attribute :roles, :string, array: true, default: []
#   end
#
#   # good
#   class User < ActiveRecord::Base
#     attribute :roles, :string, array: true, default: -> { [] }
#   end
# 
#   bad
#   class User < ApplicationRecord
#     attribute :configuration, default: {}
#   end
#
#   # good
#   class User < ActiveRecord::Base
#     attribute :configuration, default: -> { {} }
#   end

This PR patches up the AttributeDefaultBlockValue cop accordingly.

Reason why array and hash literals should also be passed as a block is the fact that defining them without one creates a class attribute, not instance.

class Simple < ActiveType::Object
  attribute :mutable_attribute, default: {}
end

[1] pry(main)> first = Simple.new
=> #<Simple mutable_attribute: {}>
[2] pry(main)> first.mutable_attribute.merge!(a: 3)
=> {:a=>3}
[3] pry(main)> second = Simple.new
=> #<Simple mutable_attribute: {:a=>3}>
[4] pry(main)> second.mutable_attribute
=> {:a=>3}
[5] pry(main)> Simple.new.mutable_attribute.object_id
=> 70340537951880
[6] pry(main)> Simple.new.mutable_attribute.object_id
=> 70340537951880

which is probably not what you want.

[koic]

Thank you for improving and explaining!