obshashrange: introduce basic sqlite caching Same as for stablerange, this is far from perfect but already a win. The cache is currently extremely volatile, but that will still be a win when doing multiple consecutive request during discovery. Better cache invalidation will happens "in the future".

stablerange: warm cache before using it server side We make sure the cache is fully up to date before starting to use it. Updating all value is more efficient and this give us a single point where we update and write on disk. Hopefully the cache have been kept up to date as we go anyway.

stablerange: warm cache before using it in findrangemissing We make sure the cache is fully up to date before starting to use it. Updating all value is more efficient and this give us a single point where we update and write on disk. Hopefully the cache have been kept up to date as we go anyway.