Fix Generation of proper migration when
  ActiveRecord::Base.pluralize_table_names = false.

  Previously, generation a migration like this:

      rails g migration add_column_name_to_user name

  would not generating the correct table name.

Fixes #13426.
Merge pull request #13440 from kuldeepaggarwal/pluralize_table_name_issue

Generating proper migration when ActiveRecord::Base.pluralize_table_names = false