QmlDesigner: Fix shader baker (qsb) file autogeneration

'-o' command line parameter was missing, so the tool interpreted
the target output file to be the source file.

Fixes: QDS-10207
Change-Id: Idb9468d56189314bfb9138e4237f7734b65cd4eb
Reviewed-by: Qt CI Patch Build Bot <ci_patchbuild_bot@qt.io>
Reviewed-by: Mahmoud Badri <mahmoud.badri@qt.io>

src/plugins/qmldesigner/designercore/instances/nodeinstanceview.cpp

@@ -2175,6 +2175,7 @@ void NodeInstanceView::handleShaderChanges()
         }
 
         QStringList args = baseArgs;
+        args.append("-o");
         args.append(outPath.toString());
         args.append(shader);
         auto qsbProcess = new Utils::Process(this);