Expose a CLI to enable/disable cached metadata optimization for prepared statements

[muzarski]

This would directly correspond to PreparedStatement::set_use_cached_metadata().

The optimization is disabled by default, due to CQL v4 limitations and known issue with SELECT * queries.
Refs:

• https://github.com/scylladb/scylla-rust-driver/blob/v1.0.0/scylla/src/statement/prepared.rs#L71-L90
• https://docs.datastax.com/en/developer/java-driver/3.0/manual/statements/prepared/index.html#avoid-preparing-select-queries

It would be nice to benchmark and compare two runs: with and without the optimizations - to see how much we gain by enabling the optimization.