Return inputs ID in --test_output_json outputs

[Delphine-L]

It would be nice to return the IDs of workflow inputs in the --test_output_json outputs when running a workflow with planemo run.

Use case :
I am auto-populating the inputs of Workflow 2 that run after Workflow 1 using the test output json. They have some inputs in common, and I either need to go to the interface and look for individual dataset IDs in a large collection or use the URLs and upload the data again.