refactor: general code base refactor (#2950)

* refactor

* fix: bug in previous refactor

* chore: exclude phpcompat sniff due to bug in phpcompat

* fix: do not leak absolute paths

* refactor/fix: batch extensions checking, fix DOS issue

lib/CacheInterface.php

@@ -55,7 +55,7 @@ interface CacheInterface
     /**
      * Returns the timestamp for the curent cache data
      *
-     * @return int Timestamp or null
+     * @return ?int Timestamp
      */
     public function getTime();