TaskTree: Prepare for de-utils-ization - part 2

Move TaskTree into Tasking namespace.
Move Tasking namespace out of Utils namespace.

Change-Id: Ib4c1d7f54f1808517e54768dfa27209c33517b61
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: hjk <hjk@qt.io>

src/plugins/remotelinux/abstractremotelinuxdeploystep.cpp

@@ -19,6 +19,7 @@
 #include <QPointer>
 
 using namespace ProjectExplorer;
+using namespace Tasking;
 using namespace Utils;
 
 namespace RemoteLinux {
@@ -204,7 +205,7 @@ bool AbstractRemoteLinuxDeployStep::isDeploymentNecessary() const
     return true;
 }
 
-Tasking::Group AbstractRemoteLinuxDeployStep::deployRecipe()
+Group AbstractRemoteLinuxDeployStep::deployRecipe()
 {
     return {};
 }