qt: Do not use QKeyEvent copy constructor

This change is preparation for Qt 6, and it fixes an experimental build
with Qt 6.2.4 as copying of `QEvent` has been disabled in Qt 6.0.0 (see
19f9b0d5f54379151eb71e98555b203ad6756276 upstream commit).

Author: hebasto

src/qt/rpcconsole.cpp

@@ -618,17 +618,16 @@ bool RPCConsole::eventFilter(QObject* obj, QEvent *event)
         case Qt::Key_Down: if(obj == ui->lineEdit) { browseHistory(1); return true; } break;
         case Qt::Key_PageUp: /* pass paging keys to messages widget */
         case Qt::Key_PageDown:
-            if(obj == ui->lineEdit)
-            {
-                QApplication::postEvent(ui->messagesWidget, new QKeyEvent(*keyevt));
+            if (obj == ui->lineEdit) {
+                QApplication::sendEvent(ui->messagesWidget, keyevt);
                 return true;
             }
             break;
         case Qt::Key_Return:
         case Qt::Key_Enter:
             // forward these events to lineEdit
-            if(obj == autoCompleter->popup()) {
-                QApplication::postEvent(ui->lineEdit, new QKeyEvent(*keyevt));
+            if (obj == autoCompleter->popup()) {
+                QApplication::sendEvent(ui->lineEdit, keyevt);
                 autoCompleter->popup()->hide();
                 return true;
             }
@@ -642,7 +641,7 @@ bool RPCConsole::eventFilter(QObject* obj, QEvent *event)
                   ((mod & Qt::ShiftModifier) && key == Qt::Key_Insert)))
             {
                 ui->lineEdit->setFocus();
-                QApplication::postEvent(ui->lineEdit, new QKeyEvent(*keyevt));
+                QApplication::sendEvent(ui->lineEdit, keyevt);
                 return true;
             }
         }