HackStudio: Add HackStudio::for_each_open_file

Author: https://github.com/itamar8910
Commit: 3e9a96f1d8
Pull-request: https://github.com/SerenityOS/serenity/pull/11157
Issue: https://github.com/SerenityOS/serenity/issues/11064

Userland/DevTools/HackStudio/HackStudioWidget.cpp

@@ -1484,4 +1484,11 @@ void HackStudioWidget::open_coredump(String const& coredump_path)
     }
 }
 
+void HackStudioWidget::for_each_open_file(Function<void(ProjectFile const&)> func)
+{
+    for (auto& open_file : m_open_files) {
+        func(*open_file.value);
+    }
+}
+
 }