fix(*): add logic to better determine if a param is internal to Porter

[vdice]

What does this change

• Adds/refactors logic to enable determining if a parameter is internal to Porter across the codebase

What issue does it fix

Now that Porter's list of internal parameters can grow beyond the classic "porter-debug", thanks to the handy parameter sources work, we needed a better way to track these so that they are hidden on porter explain, not eligible for generation in porter parameters generate, etc.

Notes for the reviewer

The approach in this fix is to designate parameters as internal via adding a standardized comment to the $comment field of the parameter's definition schema. This seemed a less fragile route than to try to manage a slice/map in memory. Are there any potential issue(s) with the approach used?

Checklist

• Unit Tests
• Documentation
• Schema (porter.yaml)

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[carolynvs]

LGTM

I'll update any of my PRs that add more parameters (like for dependency sources) so that they set the comment as well.