[EPIC] Metaschema enhancments to support OSCAL modeling

[david-waltermire]

User Story:

As an OSCAL model developer, I need to take advantage of a number of metaschema enhancements. This epic tracks a set of metaschema enhancements that have been planned.

Goals:

The following issues need to be completed:

• Complete coverage of JSON Schema production unit tests (Complete coverage of JSON Schema production unit tests metaschema#18)
• Move Metaschema documentation and code to a new GitHub Repository (Move Metaschema documentation and code to a new GitHub Repository #596)
• Support valid OSCAL fragments (Valid OSCAL File Fragments #590)

Dependencies:

None.

Acceptance Criteria

• All OSCAL website and readme documentation affected by the changes in this issue have been updated. Changes to the OSCAL website can be made in the docs/content directory of your branch.
• 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.

[david-waltermire]

I am going to close this epic since the metaschema portions are completed. We will continue work on issue #590.