Update comparison to use new rule id as primary identifier.

[ksharper]

Legacy Rule ID are of format SV-86473r2_rule and new format is SV-204392r505924_rule
The part of the Rule ID before r will be stable across revisions/versions and is becoming the new primary identifier.
For example SV-86473 will be identical across generation of the same STIG.

inspec_delta needs to start using the rule id prior to the 'r' as the primary identifier.