Do not process user input during saving operations

Fixes a race condition in the saving process, which is caused by
processing user input events in multiple places during save.

BUG: 409395

libs/ui/KisDocument.cpp

@@ -442,7 +442,7 @@ public:
 
         if (!m_locked) {
             m_image->requestStrokeEnd();
-            QApplication::processEvents();
+            QApplication::processEvents(QEventLoop::ExcludeUserInputEvents);
 
             // one more try...
             m_locked = std::try_lock(m_imageLock, m_savingLock) < 0;
@@ -777,7 +777,7 @@ void KisDocument::setFileBatchMode(const bool batchMode)
 KisDocument* KisDocument::lockAndCloneForSaving()
 {
     // force update of all the asynchronous nodes before cloning
-    QApplication::processEvents();
+    QApplication::processEvents(QEventLoop::ExcludeUserInputEvents);
     KisLayerUtils::forceAllDelayedNodesUpdate(d->image->root());
 
     KisMainWindow *window = KisPart::instance()->currentMainwindow();

libs/ui/dialogs/kis_delayed_save_dialog.cpp

@@ -94,7 +94,7 @@ void KisDelayedSaveDialog::blockIfImageIsBusy()
     t.start();
 
     while (t.elapsed() < m_d->busyWait) {
-        QApplication::processEvents();
+        QApplication::processEvents(QEventLoop::ExcludeUserInputEvents);
 
         if (m_d->checkImageIdle()) {
             setResult(Accepted);

libs/ui/kis_async_action_feedback.cpp

@@ -52,7 +52,7 @@ T runActionImpl(std::function<T()> func)
     watcher.setFuture(result);
 
     while (watcher.isRunning()) {
-        qApp->processEvents();
+        qApp->processEvents(QEventLoop::ExcludeUserInputEvents);
     }
 
     watcher.waitForFinished();
@@ -71,7 +71,7 @@ void KisAsyncActionFeedback::runVoidAction(std::function<void()> func)
     watcher.setFuture(result);
 
     while (watcher.isRunning()) {
-        qApp->processEvents();
+        qApp->processEvents(QEventLoop::ExcludeUserInputEvents);
     }
 
     watcher.waitForFinished();
@@ -80,7 +80,7 @@ void KisAsyncActionFeedback::runVoidAction(std::function<void()> func)
 void KisAsyncActionFeedback::waitForMutex(QMutex *mutex)
 {
     while (!mutex->tryLock()) {
-        qApp->processEvents();
+        qApp->processEvents(QEventLoop::ExcludeUserInputEvents);
     }
 
     mutex->unlock();