fix: rename tests files and add namespace according to review

Author: ga-devfront

tests/PHPStan/Rules/Variables/DefinedVariableRuleTest.php

@@ -1169,14 +1169,14 @@ public function testBug8719(): void
 		$this->analyse([__DIR__ . '/data/bug-8719.php'], []);
 	}
 
-	public function testDynamicVariableInsideIsset(): void
+	public function testBug13353(): void
 	{
 		$this->cliArgumentsVariablesRegistered = true;
 		$this->polluteScopeWithLoopInitialAssignments = true;
 		$this->checkMaybeUndefinedVariables = true;
 		$this->polluteScopeWithAlwaysIterableForeach = true;
 
-		$this->analyse([__DIR__ . '/data/dynamic-variable-inside-isset.php'], [
+		$this->analyse([__DIR__ . '/data/bug-13353.php'], [
 			[
 				'Variable $bar might not be defined.',
 				9,

tests/PHPStan/Rules/Variables/data/dynamic-variable-inside-isset.php renamed to tests/PHPStan/Rules/Variables/data/bug-13353.php

@@ -1,5 +1,7 @@
 <?php declare(strict_types = 1);
 
+namespace Bug13353;
+
 $foo = 'bar';
 
 if (!isset($$foo)) {