Rename the Configured filter on processes to Started

The concept of a process being configured or not really only works for Workers and Dataset processes; you cannot resume configuring a Git process for example. The Configured filter in the process list actually looks for processes that have or do not have any tasks. We could rename the filter to Started/Not started, although this does not work when a process has been cleaned up by arkindex cleanup since it won't have any tasks anymore. We could change that filter to use Process.started != None instead.