[BUGFIX] Make getHasChildNodeSelected recursive

Currently, the GetHasChildNodeSelected function in \ApacheSolrForTypo3\Solr\Domain\Search\ResultSet\Facets\OptionBased\Hierarchy\Node only checks whether a direct child is selected. With hierarchical filters, however, it makes sense to check whether any child is selected in this hierarchy branch. E.g. because this should be expanded in the frontend.
```html 
<f:if condition="{childNode.hasChildNodeSelected}">
  <f:variable name="detailsState" value="open" />
</f:if>
```

The PR implements this recursive check.

Fixes: #4155

Classes/Domain/Search/ResultSet/Facets/OptionBased/Hierarchy/Node.php

@@ -72,7 +72,7 @@ public function getHasChildNodeSelected(): bool
     {
         /** @var Node $childNode */
         foreach ($this->childNodes as $childNode) {
-            if ($childNode->getSelected()) {
+            if ($childNode->getSelected() || $childNode->getHasChildNodeSelected()) {
                 return true;
             }
         }

Tests/Unit/Domain/Search/ResultSet/Facets/OptionBased/Hierarchy/NodeTest.php

@@ -18,6 +18,7 @@
 use ApacheSolrForTypo3\Solr\Domain\Search\ResultSet\Facets\OptionBased\Hierarchy\HierarchyFacet;
 use ApacheSolrForTypo3\Solr\Domain\Search\ResultSet\Facets\OptionBased\Hierarchy\Node;
 use ApacheSolrForTypo3\Solr\Tests\Unit\SetUpUnitTestCase;
+use PHPUnit\Framework\Attributes\DataProvider;
 use PHPUnit\Framework\Attributes\Test;
 
 /**
@@ -40,35 +41,41 @@ public function canGetHasParentNode(): void
     }
 
     #[Test]
-    public function canGetHasChildNodeSelectedReturnFalseWhenNoChildNodeWasAssigned(): void
-    {
-        $facetMock = $this->createMock(HierarchyFacet::class);
-        $node = new Node($facetMock);
+    #[DataProvider('provideGetHasChildNodeSelectedDataSet')]
+    public function canHandleGetHasChildNodeSelected(
+        bool $expectedResult,
+        array $childNodes,
+    ): void {
+        $node = $this->convertDataToNode(['children' => $childNodes]);
 
-        self::assertFalse($node->getHasChildNodeSelected(), 'Node without childnodes should not indicate that it as a selected child node');
+        self::assertSame($expectedResult, $node->getHasChildNodeSelected());
     }
 
-    #[Test]
-    public function canGetHasChildNodeSelectedReturnFalseWhenNoSelectedChildNodeWasAssigned(): void
+    private function convertDataToNode(array $data): Node
     {
-        $facetMock = $this->createMock(HierarchyFacet::class);
-        $node = new Node($facetMock);
+        $node = new Node(
+            $this->createMock(HierarchyFacet::class),
+            null,
+            '',
+            '',
+            '',
+            0,
+            $data['selected'] ?? false
+        );
 
-        $childNode = new Node($facetMock, $node);
-        $node->addChildNode($childNode);
+        foreach (\array_map([$this, 'convertDataToNode'], $data['children'] ?? []) as $childNode) {
+            $node->addChildNode($childNode);
+        }
 
-        self::assertFalse($node->getHasChildNodeSelected(), 'Node with only unselected childnodes should not indicate that it has a selected child node');
+        return $node;
     }
 
-    #[Test]
-    public function canGetHasChildNodeSelectedReturnTrueWhenSelectedChildNodeWasAssigned(): void
+    public static function provideGetHasChildNodeSelectedDataSet(): iterable
     {
-        $facetMock = $this->createMock(HierarchyFacet::class);
-        $node = new Node($facetMock);
-
-        $selectedChildNode = new Node($facetMock, $node, '', '', '', 0, true);
-        $node->addChildNode($selectedChildNode);
-
-        self::assertTrue($node->getHasChildNodeSelected(), 'Node with selected child node should indicate that it has a selected child node');
+        yield 'No child nodes' => [false, []];
+        yield 'One direct child node: selected' => [true, [['selected' => true]]];
+        yield 'One direct child node: not selected' => [false, [['selected' => false]]];
+        yield 'Child node 1 level down: selected' => [true, [['selected' => false, 'children' => [['selected' => true]]]]];
+        yield 'Child node 2 levels down: selected' => [true, [['selected' => false, 'children' => [['selected' => false, 'children' => [['selected' => true]]]]]]];
     }
 }