qt: Revamp ClientModel code to handle ShowProgress core signal

No behavior change.

Author: hebasto

src/qt/clientmodel.cpp

@@ -236,15 +236,6 @@ void ClientModel::updateBanlist()
 }
 
 // Handlers for core signals
-static void ShowProgress(ClientModel *clientmodel, const std::string &title, int nProgress)
-{
-    // emits signal "showProgress"
-    bool invoked = QMetaObject::invokeMethod(clientmodel, "showProgress", Qt::QueuedConnection,
-                              Q_ARG(QString, QString::fromStdString(title)),
-                              Q_ARG(int, nProgress));
-    assert(invoked);
-}
-
 static void NotifyNumConnectionsChanged(ClientModel *clientmodel, int newNumConnections)
 {
     // Too noisy: qDebug() << "NotifyNumConnectionsChanged: " + QString::number(newNumConnections);
@@ -306,7 +297,10 @@ static void BlockTipChanged(ClientModel* clientmodel, SynchronizationState sync_
 void ClientModel::subscribeToCoreSignals()
 {
     // Connect signals to client
-    m_handler_show_progress = m_node.handleShowProgress(std::bind(ShowProgress, this, std::placeholders::_1, std::placeholders::_2));
+    m_handler_show_progress = m_node.handleShowProgress(
+        [this](const std::string& title, int progress, [[maybe_unused]] bool resume_possible) {
+            Q_EMIT showProgress(QString::fromStdString(title), progress);
+        });
     m_handler_notify_num_connections_changed = m_node.handleNotifyNumConnectionsChanged(std::bind(NotifyNumConnectionsChanged, this, std::placeholders::_1));
     m_handler_notify_network_active_changed = m_node.handleNotifyNetworkActiveChanged(std::bind(NotifyNetworkActiveChanged, this, std::placeholders::_1));
     m_handler_notify_alert_changed = m_node.handleNotifyAlertChanged(std::bind(NotifyAlertChanged, this));