Merge pull request rails#45669 from adrianna-chang-shopify/ac-allow-change-table-to-specify-base

Allow base for `Table` schema definition to be injected into `#change_table`

Author: eileencodes

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

@@ -474,13 +474,13 @@ def drop_join_table(table_1, table_2, **options)
       #  end
       #
       # See also Table for details on all of the various column transformations.
-      def change_table(table_name, **options)
+      def change_table(table_name, base = self, **options)
         if supports_bulk_alter? && options[:bulk]
           recorder = ActiveRecord::Migration::CommandRecorder.new(self)
           yield update_table_definition(table_name, recorder)
           bulk_change_table(table_name, recorder.commands)
         else
-          yield update_table_definition(table_name, self)
+          yield update_table_definition(table_name, base)
         end
       end