[connector] Implement Redis sink (XADD/SET/PUBLISH)

[josedab]

Implement Redis Sink Connector

Implement the redis-sink connector from the hub catalog.
Support three Redis operations: XADD (Streams), SET, and PUBLISH.

Config keys: url, command, key_field, stream_name
Pattern: Follow SinkConnector trait in src/connect/native.rs

Run: cargo test