Cleanup of models and data

[wendellpiez]

Addressing #473: subcontrol has been replaced by control everywhere in SP800-53.

Remaining to do (at time of writing): adjusting profile and higher models to address controls only, never subcontrols.

Also in this PR, an adjustment to the Metaschema Schematron, see #465, #475 - overriding declarations are now detected and reported as errors.

All Submissions:

• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?
• Have you squashed any non-relevant commits and commit messages? [instructions]
• Do all automated CI/CD checks pass? tbd

Changes to Core Features:

• Have you added an explanation of what your changes do and why you'd like us to include them? See Issue Syntax Modification: control/subcontrol #473
• Have you written new tests for your core changes, as applicable? n/a
• Have you included examples of how to use your new feature(s)? n/a
• Have you updated all OSCAL website and readme documentation affected by the changes you made? Changes to the OSCAL website can be made in the docs/content directory of your branch. Metaschema changes should propagate through docs

[wendellpiez]

Also addresses #471

[david-waltermire]

LGTM

[wendellpiez]

Also addresses #475 as noted above.

[david-waltermire]

LGTM