Repurpose command to create a full widget library scaffold

[agubler]

Proposal

Current the existing cli-create-widget command is used to create a single widget in a project (with test/css files etc), this is confusing as the cli-build-app provides a scaffold for a complete application project. With the new widget library build tooling, theme build tooling and dojo/parade we should consider repurposing this command to scaffold a complete widget library project.

This would provide symmetry with the cli-build-app command and I believe more valuable overall.