HackStudio: Warn of unsaved changes before making a new project

Before, the warning dialog would be opened after the NewProjectDialog,
leading to focus-fighting by the two windows. This fixes that and makes
the action more consistent with the standard serenity way of handling
unsaved changes by asking before the NewProjectDialog is brought up.
The way this is achieved avoids having to rewrite open_project as well.

Userland/DevTools/HackStudio/HackStudioWidget.cpp

@@ -703,6 +703,12 @@ NonnullRefPtr<GUI::Action> HackStudioWidget::create_delete_action()
 NonnullRefPtr<GUI::Action> HackStudioWidget::create_new_project_action()
 {
     return GUI::Action::create("&Project...", Gfx::Bitmap::try_load_from_file("/res/icons/16x16/hackstudio-project.png"sv).release_value_but_fixme_should_propagate_errors(), [this](const GUI::Action&) {
+        if (warn_unsaved_changes("There are unsaved changes. Would you like to save before creating a new project?") == ContinueDecision::No)
+            return;
+        // If the user wishes to save the changes, this occurs in warn_unsaved_changes. If they do not,
+        // we need to mark the documents as clean so open_project works properly without asking again.
+        for (auto& editor_wrapper : m_all_editor_wrappers)
+            editor_wrapper.editor().document().set_unmodified();
         auto dialog = NewProjectDialog::construct(window());
         dialog->set_icon(window()->icon());
         auto result = dialog->exec();