Update OSCAP job to allow for CaC version or URL to be set

Background

The compliance as code (CaC) releases for UBI use a version specified by an in repo file. We should allow for the version to be set in a GitLab CI variable, to test an updated CaC version, and if the variable is not provided, pull it from the file in the IB pipeline repo. We should also allow for the URL to the SCAP content to be set as well. This would allow for testing updates to the Ubuntu SCAP content.

AC

• Can use a CI var to override the CaC release version defined in repo
• Can omit using a CI var to define the CaC release version, and the in repo version is used
• Can use a CI var to override the SCAP content URL, defined in repo
• Can omit using a CI var to define the SCAP content URL, and the in repo value is used