Provide ability to put content of multiple modules in a single shard

Currently we have 2 options. Create a shard per module and put the all the modules which do not have a configured shard into the default shard. It would be nice if we could have the data for some related modules stored together in one shard. This will help us distribute data better across a cluster without forcing us to configure one shard per module which has it's own overhead (RAFT related heartbeats and such)