Review performance homepage

[marceltectonica]

Preload background image homepage hero

https://github.com/Tectonica-Campaigns-Solutions/ga-egp/blob/66d7a7765aa7961368155c021e1b8d2dcbe02bcd/gatsby-ssr.js#L15

This image should be dynamic

https://www.gatsbyjs.com/docs/reference/config-files/gatsby-ssr/

Query to homepage and return homepage hero image url