DROP sharded table

[donhardman]

We should add functionality to support dropping shared tables. The command should clean up everything associated with the shared table. To make this happen, we should start with a special command DROP SHARDED TABLE. After that, we'll migrate to use the DROP TABLE command, while the daemon should detect if it's a shared table or not and process the request accordingly.

This requires modifications on the daemon side, so we'll start with the DROP SHARDED TABLE syntax first.