feat(staticMaps): Add concurrency and caching to speed up static maps
feat(staticMaps): Add concurrency and caching to speed up static maps

NB: Caching will not be noticable in dev, because currently npm start
and npm run dev will turn off http caching, but have tested this works
when http caching is enabled.

digidem/ecuador-map-editor,digidem/ecuador-map-editor