Remove inline metadata from models

[xee5ch]

User Story

As a developer of systems that exchange security and risk assessment data, I would prefer that OSCAL models do not require OSCAL data to have inline metadata. Given its use in APIs, I would much prefer that metadata be "enveloped" externally as you would expect from results from a REST-based API service.

Goals

• Simplify software that programmatically generates OSCAL data.
• Simplify software that programmatically consumes and processes OSCAL data, especially as responses in REST API calls.

Dependencies

No response

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.

(For reviewers: The wiki has guidance on code review and overall issue review for completeness.)

Revisions

No response