Overhaul area maps

[vnugent]

See it in action: https://openbeta.io/maps

Parent issue to track improvements to area maps

• [x] #1058
• [x] #1060 (Need rework due to migration to self-hosting)
• [x] #1076
• [x] Host our own crag maptiles https://github.com/OpenBeta/openbeta-graphql/pull/394

[vnugent]