deploy styleguide to fermyon cloud

[flynnduism]

Summary

This PR turns the static HTML styleguide site into a light Wasm app via Spin).

• Adds Spin config files
• Adds Bartholomew structure and switches pages from HTML to HBS
• Update relative file paths for assets to use {{site.info.base_url}}
• TODO: figure out TLS

Hosting

This restructuring is intended to change where/how the site runs:

// runs on Netlify as a static site with Parcel.js
https://fermyon-styleguide.netlify.app 

to 

// running on Fermyon Cloud as a WebAssembly app with Spin
https://fermyon-styleguide.netlify.app/

[netlify]

👷 Deploy Preview for fermyon-styleguide processing.

Name	Link
🔨 Latest commit	44bb94c
🔍 Latest deploy log	https://app.netlify.com/sites/fermyon-styleguide/deploys/656cc3d7328f49000813b97c