Improve Symfony detection

Various ways to detect Symfony when it's running in debug mode

src/apps.json

@@ -10297,6 +10297,13 @@
       "cats": [
         18
       ],
+      "cookies": {
+        "sf_redirect": ""
+      },
+      "html": "(?:<div id=\"sfwdt[^\"]+\" class=\"[^\"]*sf-toolbar|<div class=\"sf-toolbar[^>]+?>[^]+<span class=\"sf-toolbar-value\">([\\d.])+)\\;version:\\1",
+      "js": {
+        "Sfjs": ""
+      },
       "icon": "Symfony.png",
       "implies": "PHP",
       "website": "http://symfony.com"