LibGUI+Userland: Make Dialog::ExecResult an enum class

Author: https://github.com/AtkinsSJ
Commit: cdffe556c8
Pull-request: https://github.com/SerenityOS/serenity/pull/14021
Reviewed-by: https://github.com/linusg ✅

Userland/Libraries/LibGUI/CommandPalette.cpp

@@ -288,7 +288,7 @@ void CommandPalette::finish_with_index(GUI::ModelIndex const& filter_index)
     auto* action = static_cast<GUI::Action*>(action_index.internal_data());
     VERIFY(action);
     m_selected_action = action;
-    done(ExecOK);
+    done(ExecResult::OK);
 }
 
 }