Switch constraint namespace checking to not use has-oscal-namespace() function

[aj-stein-gsa]

User Story

As a developer of Metaschema-enabled tools for OSCAL-based software, in order to make development and use of tooling easier to development and maintain, I would like all in-model constraints to use target="field/@ns = 'http://csrc.nist.gov/ns/oscal'" in place of target="fieldt[has-oscal-namespace('http://csrc.nist.gov/ns/oscal')" to simplify development of tooling and not require of custom OSCAL-specific Metaschema functions not in the core library.

Goals

• Simplify model development and maintenance
• Allow developers who have not implemented the fn:has-oscal-namspace() function (so those others than the NIST oscal-cli and community forks) to more easily develop and maintain software processing complex allowed-value enumerations

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