Add atlas server map caching

[m3taphysics]

Description

We currently redownload the entire map on each load of the unity renderer. But the map itself doesn't change this frequently. This endpoint can be contacted first before deciding to redownload the map and use the disk cache if so.

https://api.decentraland.org/v2/tiles/info

Deliverables

• [ ] Only download the map if it has actually been updated since last download

Notes

A more granular approach of determining which map chunk was updated previously was discussed but for now we should determine the impact of this first.