Add support for REPLICA IDENTIFY FULL

[meskill]

Currently the pgdog doesn't support REPLICA IDENTIFY FULL configuration. During #914 the proper validation upfront of copy has been added to catch this early before making the copy since otherwise it was expecting to fail during the replication stage.

But, maybe we can improve this on pgdog side:

1. Modify table validation to accept IDENTIFY FULL
2. Add custom statement generation for queries to support full identity (ignore toasted, not distinct for queries etc.)
3. Verify the use cases where it can fail and add helpful logs where possible