Add food group dot map

[oliverroick]

Implements #56: Adds the food group map

• Adds a new layer with the tiles that I uploaded to Mapbox
• Configures the style based on the z-Score normalised map
• Adds a cartography module, which provides the map styles, move the styles for the area-layer over
• Remove the @types/mapbox-gl dependency. MapboxGL has moved to first-class TypeScript support, the community types are now outdated.