Add module scaffold script to larva binary

[laras126]

In the VY theme there is a script to scaffold files for a modules. This should exist in the shared larva package scripts, be tested, and available via the larva binary so themes can register larva scaffold in the same manner as the other scripts.

Here is the script: https://gist.github.com/laras126/9500f99d9d67b9e67f80c915a267608e

We should use a CLI prompt tool like inquirer: https://www.npmjs.com/package/inquirer

And generate the templates with mustache (or Twig since we have that already?) instead of programmatically writing the files. See the scaffold in pmc-plugins/pmc-gutenberg/bin/scaffold.js for an example.