Tasking::Transfer: Rename Transfer into FileTransferTask

Rename TransferTest into FileTransferTestTask.
Rename adapters accordingly.

Task-number: QTCREATORBUG-29102
Change-Id: I50c8b8d64abd7d3063044eaf2e0daceb01e8d388
Reviewed-by: hjk <hjk@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>

src/plugins/remotelinux/rsyncdeploystep.cpp

@@ -134,7 +134,7 @@ TaskItem RsyncDeployStep::transferTask()
                             + "\n" + result.m_errorString);
         }
     };
-    return Transfer(setupHandler, {}, errorHandler);
+    return FileTransferTask(setupHandler, {}, errorHandler);
 }
 
 Group RsyncDeployStep::deployRecipe()