Make ASpace helper_methods into a gem

[regineheberlein]

Background

We want to add aspace2alma to lib_jobs. Since ad-hoc jobs not moving to lib_jobs rely on the same helper_methods, we want to turn the methods file into a gem so it can be used by both processes.

Acceptance criteria

• All the methods in the file work from the gem
• The gem is included in aspace_helpers as well as lib_jobs
• The gem has tests for all the methods
• The gem has rubocop linting

Implementation notes

We can do this using bundler