Add named argument tests for PDOStatement::fetchAll()

The `mode:` named argument works correctly with the multi-variant
overloads. Note that `column:` and `class:` cannot be used as named
arguments because PDOStatement::fetchAll is an internal function with
variadic `...$args` — PHP does not accept arbitrary named parameters
for variadic params on internal functions.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: phpstan-bot

tests/PHPStan/Rules/Methods/data/bug-5509.php

@@ -25,5 +25,10 @@ public function test(\PDOStatement $stmt): void
 
 		// With just mode - should not error
 		$stmt->fetchAll(\PDO::FETCH_ASSOC);
+
+		// Named arguments
+		$stmt->fetchAll(mode: \PDO::FETCH_DEFAULT);
+		$stmt->fetchAll(mode: \PDO::FETCH_COLUMN);
+		$stmt->fetchAll(mode: \PDO::FETCH_CLASS);
 	}
 }