[TASK] Improve type annotations for GU::locationHeaderUrl

This helps PHPStan better analyse code that uses this method.

Resolves: #99133
Releases: main, 11.5
Change-Id: Ia6da1e1f25a9bfd0f493b2c1e244d79aab865c56
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/76677


Tested-by: core-ci <typo3@b13.com>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>

typo3/sysext/core/Classes/Utility/GeneralUtility.php

@@ -2203,7 +2203,7 @@ class GeneralUtility
      * - Otherwise prefixed with TYPO3_REQUEST_DIR (relative to current dir / TYPO3_REQUEST_DIR)
      *
      * @param string $path URL / path to prepend full URL addressing to.
-     * @return string
+     * @return ($path is non-empty-string ? non-empty-string : string)
      */
     public static function locationHeaderUrl($path)
     {