HackStudio: Set proper action scope for editor shortcuts

This fixes issue #14429. The editor actions were not given a parent as
scope so defaulted to global. Because HackStudio can have multiple
editors and even multiple editor tab widgets, I chose the
VerticalSplitter that all editor tab widgets get added to as the parent.
With a Widget set as the parent, the action gets WidgetLocal scope and
allows the embedded terminals to receive shortcuts.

Thanks to Andreas for doing a quick look at this and pointing in the
right direction during an Office Hours stream :)

Userland/DevTools/HackStudio/HackStudioWidget.cpp

@@ -1257,12 +1257,12 @@ void HackStudioWidget::create_toolbar(GUI::Widget& parent)
     toolbar.add_action(*m_delete_action);
     toolbar.add_separator();
 
-    toolbar.add_action(GUI::CommonActions::make_cut_action([this](auto&) { current_editor().cut_action().activate(); }));
-    toolbar.add_action(GUI::CommonActions::make_copy_action([this](auto&) { current_editor().copy_action().activate(); }));
-    toolbar.add_action(GUI::CommonActions::make_paste_action([this](auto&) { current_editor().paste_action().activate(); }));
+    toolbar.add_action(GUI::CommonActions::make_cut_action([this](auto&) { current_editor().cut_action().activate(); }, m_editors_splitter));
+    toolbar.add_action(GUI::CommonActions::make_copy_action([this](auto&) { current_editor().copy_action().activate(); }, m_editors_splitter));
+    toolbar.add_action(GUI::CommonActions::make_paste_action([this](auto&) { current_editor().paste_action().activate(); }, m_editors_splitter));
     toolbar.add_separator();
-    toolbar.add_action(GUI::CommonActions::make_undo_action([this](auto&) { current_editor().undo_action().activate(); }));
-    toolbar.add_action(GUI::CommonActions::make_redo_action([this](auto&) { current_editor().redo_action().activate(); }));
+    toolbar.add_action(GUI::CommonActions::make_undo_action([this](auto&) { current_editor().undo_action().activate(); }, m_editors_splitter));
+    toolbar.add_action(GUI::CommonActions::make_redo_action([this](auto&) { current_editor().redo_action().activate(); }, m_editors_splitter));
     toolbar.add_separator();
 
     toolbar.add_action(*m_build_action);