[golemfactory/golem] Client.{create,restart}_task: restore returning task id (#3031)

The only problem is, it takes too much time to create task, or at least «response» from the «create task» definition, if the task file is heavy/detailed or etc. The return/response shouldn’t wait for the task to be created. It was a known problem some time ago and solved by the team, but this branch cause it again.