Migrate frontend and backend repo into mono-repo

[Decipher]

Is your feature request related to a problem? Please describe.
As a maintainer I want a single mono-repo to maintain both the frontend and backend.

Describe the solution you'd like

• Change the repository into a mono-repo style setup: https://github.com/druxt/quickstart-druxt-site
• Migrate https://github.com/druxt/demo-api.druxtjs.org into /drupal
• Update Lagoon integration
• Update demo domains to https://*.umami.demo.druxtjs.org
  • Frontend
  • Backend
  • Storybook
• Create new demo.druxtjs.org with link to Umami and "coming soon" demos.
  • https://github.com/druxt/demo.druxtjs.org
  • https://6318632f24607c184f2e2459--test-demo-druxtjs-org.netlify.app/

Describe alternatives you've considered
N/A

Additional context
N/A