Convert system schema tables to/from system_schema tables

[mpenick]

Older versions of driver use to use schema tables that lived under system, but newer versions of Cassandra and DSE have removed those tables in favor of tables under system_schema. The proxy would have to intercept these queries and convert them to the new tables.

To make the connection process work for older driver that use schema tables under system the proxy currently return empty tables. In the future we could intercept these and return actual values if needed.