test(aot): add test case for return value by reference method

- Create new test file return-by-ref-method.phpt
- Add test class with private value property
- Implement getValue method returning copy of value
- Implement getRefValue method returning reference to value
- Test both regular and reference return behaviors
- Verify reference assignment modifies original value
- Add expected output with proper integer dumps

tests/aot/ref/return-by-ref-method.phpt

@@ -0,0 +1,34 @@
+--TEST--
+Return value by reference (method)
+--FILE--
+<?php
+class Test
+{
+    private $value = 1;
+
+    public function getValue()
+    {
+        return $this->value;
+    }
+
+    public function &getRefValue()
+    {
+        return $this->value;
+    }
+}
+
+function main()
+{
+    $test = new Test;
+    var_dump($test->getValue());
+    var_dump($refValue = &$test->getRefValue());
+    $refValue = 2;
+    var_dump($test->getValue());
+    var_dump($test->getRefValue());
+}
+?>
+--EXPECT--
+int(1)
+int(1)
+int(2)
+int(2)