Ensure clip load and proxy tasks stay alove until the clip is fully loaded in Bin, to limit threads when importing/proxying many clips

src/jobs/cliploadtask.cpp

@@ -793,7 +793,7 @@ void ClipLoadTask::run()
             if (transcode) {
                 producer->set("_wait_for_transcode", 1);
             }
-            QMetaObject::invokeMethod(binClip.get(), "setProducer", Qt::QueuedConnection, Q_ARG(std::shared_ptr<Mlt::Producer>, std::move(producer)),
+            QMetaObject::invokeMethod(binClip.get(), "setProducer", Qt::BlockingQueuedConnection, Q_ARG(std::shared_ptr<Mlt::Producer>, std::move(producer)),
                                       Q_ARG(bool, true));
             if (checkProfile && !isVariableFrameRate && seekable) {
                 pCore->bin()->shouldCheckProfile = false;

src/jobs/proxytask.cpp

@@ -409,7 +409,7 @@ void ProxyTask::run()
             }
         } else if (binClip) {
             // Job successful
-            QMetaObject::invokeMethod(binClip.get(), "updateProxyProducer", Qt::QueuedConnection, Q_ARG(QString, dest));
+            QMetaObject::invokeMethod(binClip.get(), "updateProxyProducer", Qt::BlockingQueuedConnection, Q_ARG(QString, dest));
         }
     } else {
         // Proxy process crashed of failed