Create demo pages for components

[ChristianMurphy]

uPortal-web-components provides demo pages for most of it's components.
E.G.

• https://uportal-contrib.github.io/uPortal-web-components/en/components/content-carousel/demo
• https://uportal-contrib.github.io/uPortal-web-components/en/components/dashboard-carousel/demo
• https://uportal-contrib.github.io/uPortal-web-components/en/components/esco-content-menu/demo
• https://uportal-contrib.github.io/uPortal-web-components/en/components/waffle-menu/demo

Each demo comes with two parts.

1. A page the includes the component and related polyfills
2. Some sample data to drive the component

It would be great to have similar demo pages for the notification web components.