Switch out Nominatim and Photon for Pelias

[ellenhp]

This reduces the memory requirements for full-planet builds to more affordable levels. It also replaces two services with one meaning fewer copies of the same data, and handles interpolation better than photon.

This requires the -P flag with earthly now because of the use of docker-in-docker during index generation.

• Update frontend
• Document need for -P flag
• Automatically determine country if possible based on BBBike extract CSV.
• Write a test plan

Test Plan:

• Check base-map functionality
• Check search auto-complete
• Check clicking on search results
• Check car routing
• Check bike routing
• Check walking routing
• Check transit routing

[ellenhp]

Memory requirements for the full planet import are 64GB and running the full planet is now about 12GB I think, maybe lower if some of the services respond to memory pressure without falling over.

This is huge, merging it. I have a working planet-scale install on my desktop now because of this work.