models: move html_data_attributes to policies.

Move html_data_attributes definitions from models to policies. Which
attributes are permitted as data-* attributes is a view level concern
and should be defined on the policy level, not the model level. Models
should be agnostic about how they're used in views.

app/models/ip_address.rb

@@ -50,10 +50,6 @@ class IpAddress < ApplicationRecord
     true
   end
 
-  def html_data_attributes
-    super & attributes.keys.map(&:to_sym)
-  end
-
   def self.searchable_includes
     [:user, :model]
   end