Check for RVM and rbenv in the asdf context

What does this Merge Request do and why?

Alerts people that are running updates to asdf things that they have RVM or rbenv installed. This isn't definitely a problem, but often is.

Merge Request checklist

• This change is backward compatible. If not, please include steps to communicate to our users.
• Tests added for new functionality. If not, please raise Issue to follow-up.
• Documentation added/updated, if needed.
• gdk doctor test added, if needed.
• Add the ~highlight label if this MR should be included in the CHANGELOG.md.