Provide a warning when matching against a group

[david-waltermire]

User Story

See usnistgov/oscal-cli#126

Goals

See usnistgov/oscal-cli#126

Dependencies

No response

Acceptance Criteria

• All website and readme documentation affected by the changes in this issue have been updated.
• A Pull Request (PR) is submitted that fully addresses the goals of this User Story. This issue is referenced in the PR.
• The CI-CD build process runs without any reported errors on the PR. This can be confirmed by reviewing that all checks have passed in the PR.

Revisions

No response

[david-waltermire]

As discussed in usnistgov/oscal-cli#126, I believe instead of warning that a group is referenced, the better thing to do is to add an error constraint that checks if the id does not match a control id in the referenced catalog or profile. In this way, if a group is referenced, then an error would be raised indicating that the referenced id is not for a control in the referenced source or resolved catalog.