[Config] Handle Phar absolute path in FileLocator

Author: alexandre-daubois

src/Symfony/Component/Config/FileLocator.php

@@ -85,6 +85,7 @@ private function isAbsolutePath(string $file): bool
                 && ('\\' === $file[2] || '/' === $file[2])
             )
             || parse_url($file, \PHP_URL_SCHEME)
+            || str_starts_with($file, 'phar:///') // "parse_url()" doesn't handle absolute phar path, despite being valid
         ) {
             return true;
         }

src/Symfony/Component/Config/Tests/FileLocatorTest.php

@@ -39,6 +39,7 @@ public static function getIsAbsolutePathTests(): array
             ['\\server\\foo.xml'],
             ['https://server/foo.xml'],
             ['phar://server/foo.xml'],
+            ['phar:///server/foo.xml'],
         ];
     }