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

Earlier, when `pluralize_table_names = false`, then if we try to create new migration then it does not consider the `ActiveRecord::Base.pluralize_table_names` configuration and always pluaralizing the table name.


```ruby
Before
rails g migration add_column_test1_to_user test1
# => 
class AddColumnTest1ToUser < ActiveRecord::Migration
  def change
    add_column :users, :test1, :string
  end
end


Now:
rails g migration add_column_test1_to_user test1
# =>
class AddColumnTest1ToUser < ActiveRecord::Migration
  def change
    add_column :user, :test1, :string
  end
end
```




fixes #13426