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fix(clickhouse): implement re_scan for nested loop joins (#546)

* fix(clickhouse): implement re_scan for nested loop joins

Fixes #532

PostgreSQL uses Nested Loop joins when joining foreign tables.
During a Nested Loop join, the inner (right) table is scanned
multiple times - once for each row of the outer table. The FDW
framework calls re_scan() to restart the inner scan for each
outer row.

The ClickHouse FDW was using the default no-op re_scan()
implementation, which meant that after the first scan completed,
subsequent rescans returned no data because:
- is_scan_complete was still true
- row_receiver channel was exhausted
- No new streaming task was spawned

This fix implements re_scan() to restart the async streaming:
- Abort existing streaming task if running
- Reset scan state flags
- Reinitialize the bounded channel
- Spawn new streaming task with the same SQL query
- Fetch the first row to initialize the rescan

Also adds integration tests for inner, left, and right joins.

* code refactor and upgrade version

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Co-authored-by: Bo Lu <lv.patrick@gmail.com>

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