Support files or URIs for metaschema-cli arguments

[aj-stein-nist]

User Story:

Placeholder

Goals:

NOTE: I have split this from its overarching work in #267 as out of scope for #241 because all commands and subcommands will have to be switched over to this approach because of the architecture for command and subcommand validation.

Dependencies:

{Describe any previous issues or related work that must be completed to start or complete this issue.}

Acceptance Criteria

• All website and readme documentation affected by the changes in this issue have been updated. Changes to the 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.

{The items above are general acceptance criteria for all User Stories. Please describe anything else that must be completed for this issue to be considered resolved.}