Migrate Apache IoTDB table-model SQL query execution from REST API to iotdb-client-go

Problem

The current REST-only query path has a few limitations:

• Every query is a separate HTTP round-trip, with no reuse of pooled native sessions.
• Per-query database selection is awkward: the REST API doesn't model the session USE state that table-model SQL expects.
• It diverges from Apache IoTDB's recommended native client usage.

Request

Support executing IoTDB 2.x table-model SQL queries through apache/iotdb-client-go, while keeping REST for metadata-only operations.

The query path should allow each request to select its target database correctly, support datasource-level RPC configuration, and preserve compatibility with existing IoTDB dashboards and queries.