Background

DistSender needs changes to work on SQL tenants. The two approaches we've discussed are either giving it an endpoint to do range lookups (and changing a bunch of stuff on how it uses gossip and other systems that won't be available) OR pushing it into the KV layer for these deployments.

Abstractly the second option seems cleaner and easier, but it's also new territory. Either way, we need to pick one and do it.