Create sub-module for ATS Recruiter version

The task is to create a sub-module machine name ats_crm_recruiter capturing the features and functionality that are only material to the ATS Recruiter version. This has currently been added directly in a separate repo, so the code for the content types that drive the core difference in the ATS Recruiter vs ATS Standard is the CRM entities. These consist of Contact, Company, and Opportunity.

These are outlined here in the ATS Spec.