Add confirmation dialog for force start (#5797)

cockatrice/src/game/deckview/deck_view_container.cpp

@@ -303,6 +303,13 @@ void DeckViewContainer::readyStart()
 
 void DeckViewContainer::forceStart()
 {
+    const auto msg = tr("Are you sure you want to force start?\nThis will kick all non-ready players from the game.");
+    const auto res =
+        QMessageBox::warning(this, tr("Cockatrice"), msg, QMessageBox::Yes | QMessageBox::No, QMessageBox::Yes);
+    if (res == QMessageBox::No) {
+        return;
+    }
+
     Command_ReadyStart cmd;
     cmd.set_force_start(true);
     cmd.set_ready(true);