Convert references to kwargs

While we aren't taking PRs with these kinds of changes just yet, they
are fine if we're actively working on the method and it makes things
easier.

activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb

@@ -306,15 +306,25 @@ def timestamps(*args)
       #  t.belongs_to(:supplier, polymorphic: true)
       #
       # See SchemaStatements#add_reference
-      def references(*args)
-        options = args.extract_options!
-        polymorphic = options.delete(:polymorphic)
-        index_options = options.delete(:index)
-        type = options.delete(:type) || :integer
+      def references(
+        *args,
+        polymorphic: false,
+        index: false,
+        type: :integer,
+        **options
+      )
+        polymorphic_options = polymorphic.is_a?(Hash) ? polymorphic : options
+        index_options = index.is_a?(Hash) ? index : {}
         args.each do |col|
           column("#{col}_id", type, options)
-          column("#{col}_type", :string, polymorphic.is_a?(Hash) ? polymorphic : options) if polymorphic
-          index(polymorphic ? %w(type id).map { |t| "#{col}_#{t}" } : "#{col}_id", index_options.is_a?(Hash) ? index_options : {}) if index_options
+
+          if polymorphic
+            column("#{col}_type", :string, polymorphic_options)
+          end
+
+          if index
+            self.index(polymorphic ? %w(type id).map { |t| "#{col}_#{t}" } : "#{col}_id", index_options)
+          end
         end
       end
       alias :belongs_to :references