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## Summary

- Enable table functions like `generate_series` and `range` to accept scalar subqueries as arguments
- Return NULL for empty scalar subqueries to align with existing scalar subquery semantics

## Changes

This PR enables SQL like:

```sql
SELECT generate_series AS install_date
FROM generate_series(
    (SELECT count() FROM numbers(10))::int,
    (SELECT count() FROM numbers(39))::int
);

Previously, table function arguments could only be constants. Now they can be scalar subqueries that return a single value.

Implementation

1. Added contains_subquery() function to detect subqueries in AST expressions
2. Added execute_subquery_for_scalar() to execute and extract scalar values from subqueries
3. Modified bind_table_args to try constant folding first, then fall back to subquery execution
4. The subquery executor is passed from the binder to enable runtime evaluation
5. Returns Scalar::Null for empty subquery results (aligns with LeftSingleJoin behavior)

Tests

• Unit Test
• Logic Test
• Benchmark Test
• No Test - Pair with the reviewer to explain why

Added tests in 02_0063_function_generate_series.test for:

• generate_series with subquery arguments
• range with subquery arguments

Type of change

• New feature (non-breaking change which adds functionality)

This change is