ocrd network client workflow: not implemented yet

[bertsky]

see https://github.com/OCR-D/core/blob/81c0b4c01eb1db54999c5db8feae120df2cc1a7b/src/ocrd_network/cli/client.py#L91

for ideas, see here, so in this case ocrd network client workflow list|download|upload|run where the latter should look like ocrd process (i.e. block)

As an extra, we could also add a non-blocking option for run which just prints the job id. (Then we should also add a command status to query it.)