Delete the old lib templates once the new hybrid lib template is available

[jonthysell]

Summary

Once the new hybird (Paper + Fabric) template is available, we'll want to completely delete the old lib template(s).

Motivation

The old lib templates are a definite dead-end, and while customers may still choose to create new (old arch) uwp apps, we need to stop the creation of new Paper-only libs (once we have a single unified lib template).

Basic Example

No response

Open Questions

No response

[jonthysell]

Moving this to 0.79, we need a corresponding update to the docs to no longer reference these.