preventing output module collision for stepchain conversion

[vlimant]

As part of the effort to allow more (all?) taskchain to convert to stepchain (https://gitlab.cern.ch/cms-ppd/dataset-management/dm-coordination/-/issues/41 https://gitlab.cern.ch/cms-ppd/technical-support/ts-coordination/-/issues/24) the "simple trick" is to modify the output module names so that there are no duplicates.

The strategy I am suggesting here (which could also be in unified ) is the following :

1. receive a wmcontrol command line with a taskchain
2. check that there isn't any duplicated output module names (with output being kept)
3. get the python config of the task
4. modify the output module name and re-upload to a new (or version?) configid+tweak
5. modify the workflow dictionary to propagate the change in output module name
6. upload the final workflow schema

of course it would be much simpler if dmwm/WMCore#11630 / dmwm/WMCore#11631 would get done.