test: Prove ArrayToFirstClassCallableRector skips internal callbacks

If a class contains array callbacks with a non-public method, they are
not converted into first-class callables. This is due to a fix for a bug
that was specific to skipping non-public methods referenced from
*outside* the owning class - there was no previous coverage for what
should happen when a callable is referenced within a valid scope.

Author: acoulton

rules-tests/Php81/Rector/Array_/ArrayToFirstClassCallableRector/Fixture/some_class_with_own_private.php.inc

@@ -0,0 +1,35 @@
+<?php
+
+namespace Rector\Tests\Php81\Rector\Array_\FirstClassCallableRector\Fixture;
+
+final class SomeClass
+{
+    public function run()
+    {
+        $name = [$this, 'name'];
+    }
+
+    private function name()
+    {
+    }
+}
+
+?>
+-----
+<?php
+
+namespace Rector\Tests\Php81\Rector\Array_\FirstClassCallableRector\Fixture;
+
+final class SomeClass
+{
+    public function run()
+    {
+        $name = $this->name(...);
+    }
+
+    private function name()
+    {
+    }
+}
+
+?>