create the rubocop that will check name of factory bot

[Ivanov-Anton]

Description:

In case when developer defines a factory in a separate file (one file equal to one factory)
the file name of such a factory should be one of these:

1. Pluralize the model name (example: country model => countries.rb)
2. model name and plus "_factory" (example: country model => country_factory.rb)

Additionally, the new robocop can be implemented with configuration options to decide what style from these two is chosen.

[Ivanov-Anton]

see how the annotate_models gem is detect factories

(spec|test)/factories/<model>_factory.rb