Fix validation constraints to properly deference and key on uri-reference values

[aj-stein-gsa]

Committer Notes

Closes #2102 and closes #2106.

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[aj-stein-gsa]

Per an update in #2103, I am proposing a more focused change to resolve this issue and that in #2102. I will update the PR text.

If possible, I would appreciate a review from the NIST Team.

[wandmagic]

nice work! this is true to the intention of the constraints and in line with previous examples self referential links prefixed by a hash.