Adds vue-starter sample add-on

[hollyschinsky]

Description

A starter add-on project built with Vue.js. It looks the same as what our basic templates generate, just written with Vue.js instead.

NOTE: This sample to help beginners new to Vue.js, which seemed useful since it's the only example we have so far. I plan to do another simple sample but with SWC configured which I'll leave off all the extra commenting as an alternative.

Motivation and Context

We didn't have any sample add-ons that use the Vue.js framework, so devs can now use this one as a starter.

How Has This Been Tested?

In Express

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• I have signed the Adobe Open Source CLA.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.