Build out and document smoke testing

[wendellpiez]

User Story:

Smoke testing in this context refers to basic testing to ensure that scripts function, are aligned properly (wrt resources and arguments), and deliver expected results when invoked.

Some very rudimentary support for this is already provided. This needs to be built out to a credible 1.0 state.

Goals:

• Define and deploy simple commands that can verify that transformations occur properly when invoked properly.
• Verify that all supported end points, from both XSLTs and XProcs, are covered, for schema generation, converter generation, documentation generation, and possibly metaschema composition (standalone).
• Document how to conduct the tests, both globally and when focused on a single toolchain, as appropriate.

Note that extending the testing beyond delivering outputs to testing those outputs (e.g. via schema validation) is not a goal for this Issue - as these requirements are identified they should go onto other Issues.

Dependencies:

None.

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.

[wendellpiez]

@nikitawootten-nist has already provided some basics.