Enhancements to runtime interfaces for content converter XSLTs

[wendellpiez]

User Story:

Prompted by discussions related to usnistgov/OSCAL#1020, there are a couple of enhancements we can consider to the XML-to-JSON and JSON-to-XML converters in the XSLT-M4 implementation, to make them more robust and easier to use.

Goals:

• better support for error conditions with configuration / resource acquisition
  • including if the wrong converter is called by mistake for the provided data (source)
• exposing a json-data parameter to pass in literal JSON instead of a file reference

Dependencies:

This can happen along with any bug repair / testing work.

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.}

[wendellpiez]

Also consider putting templates in both stylesheets into (default) modes; currently because both directions are implemented in template sets in no-mode, they cannot be imported into the same XSLT cleanly.

[wendellpiez]

Also better stress testing of runtimes and error reporting (evaluation of text value templates etc.)