[BUGFIX] Respect templateName for fluid template assets rendering

Rendering assets in fluid templates via the special
"HeaderAssets" and "FooterAssets" sections does now
properly work with a given "templateName" by rendering
the "view" before assets rendering takes place, as this
does internally correctly set the template name.

Resolves: #105390
Releases: main, 13.4
Change-Id: I7cb102a79c35a3e054d5d7d93027c5c9609aba20
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/86687
Tested-by: core-ci <typo3@b13.com>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Oliver Bartsch <bo@cedev.de>

Author: stefanr

typo3/sysext/frontend/Classes/ContentObject/FluidTemplateContentObject.php

@@ -135,9 +135,11 @@ public function render($conf = []): string
         $variables = $this->contentDataProcessor->process($this->cObj, $conf, $variables);
         $view->assignMultiple($variables);
 
+        // Rendering the view internally set's the template (paths). This is required for following asset rendering
+        $content = $view->render($templateFilename);
+
         $this->renderFluidTemplateAssetsIntoPageRenderer($view, $variables);
 
-        $content = $view->render($templateFilename);
         if (isset($conf['stdWrap.'])) {
             return $this->cObj->stdWrap($content, $conf['stdWrap.']);
         }

typo3/sysext/frontend/Tests/Functional/Fixtures/Extensions/test_fluid_template/Configuration/TypoScript/assets.typoscript

@@ -1,6 +1,8 @@
 page = PAGE
 page.10 = FLUIDTEMPLATE
 page.10 {
-  template = TEXT
-  template.value = <f:section name="HeaderAssets">Foo Header</f:section><f:section name="FooterAssets">Foo Footer</f:section>
+  templateName = AssetsSections
+  templateRootPaths {
+    10 = EXT:test_fluid_template/Resources/Private/Templates
+  }
 }

typo3/sysext/frontend/Tests/Functional/Fixtures/Extensions/test_fluid_template/Resources/Private/Templates/AssetsSections.html

@@ -0,0 +1 @@
+<f:section name="HeaderAssets">Foo Header</f:section><f:section name="FooterAssets">Foo Footer</f:section>