Show the map overlays on a statically built site

[jamiefolsom]

The Global Writing Cultures map has two extra layers: a GeoJSON layer the site serves itself, and the DARE layer, whose map tiles come from an outside server. On a static site the GeoJSON file ships with the site as a plain file, and the DARE layer can keep loading from its own server.

Given:

• The Global Writing Cultures map layer settings.
• The GeoJSON file should stay at the path the site uses today. The _fds/maps/overlays/ folder is reserved for other files.
• react-components Netlify redirects causing cross origin errors in Tina Visual Editor #594 and Add certainty radius to bounding box #609 are known bugs in the same layer code. If they get in the way, fix them in react-components.

Update the site so that:

• both layers show on a static build of Global Writing Cultures, and turning them on and off works as it does on the live site.

Does anything about how these layers load today depend on a server?

Part of #711