Refactor packages factory to multiple files

Summary

The packages factory file is getting quite long and can be difficult to navigate. We should split it into multiple files.

Improvements

Easier to navigate code, less chance of errors or duplication.

Risks

Involved components

https://gitlab.com/gitlab-org/gitlab/blob/235490-generic-packages/generic-type/spec/factories/packages.rb

Optional: Intended side effects

Optional: Missing test coverage