bug #60820 [TypeInfo] Fix handling ConstFetchNode (norkunas)

This PR was squashed before being merged into the 7.2 branch.

Discussion
----------

[TypeInfo] Fix handling `ConstFetchNode`

| Q             | A
| ------------- | ---
| Branch?       | 7.2
| Bug fix?      | yes
| New feature?  | no
| Deprecations? | no
| Issues        | Fix #...
| License       | MIT

I cannot upgrade to 7.3 because I get:

```
  In StringTypeResolver.php line 88:
!!
!!    Cannot resolve "array{requirement: ProductLicense::SYSTEM_REQUIREMENT_*, va
!!    lue: non-empty-string}".
!!
!!
!!  In StringTypeResolver.php line 142:
!!
!!    Unhandled "PHPStan\PhpDocParser\Ast\ConstExpr\ConstFetchNode" constant expr
!!    ession.
!!
```

Commits
-------

03cc6071c59 [TypeInfo] Fix handling `ConstFetchNode`

Author: nicolas-grekas

Tests/Normalizer/ObjectNormalizerTest.php

@@ -748,6 +748,8 @@ public function testDoesntHaveIssuesWithUnionConstTypes()
         $serializer = new Serializer([new ArrayDenormalizer(), new DateTimeNormalizer(), $normalizer]);
 
         $this->assertSame('bar', $serializer->denormalize(['foo' => 'bar'], (new class {
+            public const TEST = 'me';
+
             /** @var self::*|null */
             public $foo;
         })::class)->foo);