Implement hero

[alexcarol]

Migrated from: https://github.com/aemsites/esri/issues/10

We should support both video background and composing images:

Composing images: Original: https://www.esri.com/en-us/capabilities/imagery-remote-sensing/capabilities/management#contact New: https://main--esri--aemsites.hlx.page/en-us/capabilities/imagery-remote-sensing/capabilities/management

Video background: Original page: https://www.esri.com/en-us/about/about-esri/overview New: https://main--esri--aemsites.hlx.page/en-us/about/about-esri/overview

• [x] Implement hero with composing images
• [x] Implement background video autoplay
• [x] #11