General Changes

• Fix correctness issue in ORDER BY queries due to improper implicit coercions.
• Fix planning failure when GROUP BY queries contain lambda expressions.
• Fix planning failure when left side of IN expression contains subqueries.
• Fix incorrect permissions check for SHOW TABLES.
• Fix planning failure when JOIN clause contains lambda expressions that reference columns or variables from the enclosing scope.
• Reduce memory usage of map_agg() and map_union().
• Reduce memory usage of GROUP BY queries.