LibCore: Add File method to determine current working directory

Author: https://github.com/timmot
Commit: 3ae64c7c3d
Pull-request: https://github.com/SerenityOS/serenity/pull/8586
Reviewed-by: https://github.com/alimpfard ✅

Userland/Libraries/LibCore/File.h

@@ -35,6 +35,7 @@ public:
 
     static bool exists(const String& filename);
     static bool ensure_parent_directories(const String& path);
+    static String current_working_directory();
 
     enum class RecursionMode {
         Allowed,