Add eager_load_paths instead of autoload_paths

[torukMnk]

Issue due uninitialized constant #198 On Rails > 5 versions.

One way to fix it is to add this to your Rails.application.configure environment file

 config.enable_dependency_loading = true

but it seems the gem should use eager_load_paths instead of autoload_paths.
https://www.bigbinary.com/blog/rails-5-disables-autoloading-after-booting-the-app-in-production

besides this change I notice an issue with factories directory when use eager_load_paths

 uninitialized constant FactoryBot (NameError)

I wonder why solidus_dev_support wants the factories at lib folder if those files are for testing only
https://github.com/solidusio/solidus_dev_support/blob/master/lib/solidus_dev_support/testing_support/factories.rb

[stale]

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