Add functionality to allow updating a profile to a new STIG version with changed Vuln IDs

[wdower]

I would like to use inspec_delta to go from the RHEL 7 profile to a RHEL 8 profile.

At present, RHEL 8's STIG controls have different Vul IDs than RHEL 7 (RHEL 7 STIG controls start with V-7, V-8, or V-9, while the RHEL 8 controls start with V-2). As a result inspec_delta will simply stub out control metadata for what it parses as "new" controls, even though I suspect that many of the controls' describe blocks for RHEL 8 will wind up being very similar to RHEL 7.

It would be very helpful if inspec_delta had a way to map new Vuln IDs to their old counterparts to allow the control code to transfer to the new profile (while still using the new STIG's tags, description, etc.).