Add support to RO-Crate Submission API from WorkflowHub

[lrodrin]

WfExS will upload RO-Crates to WorkflowHub. So, WfExS should support uploading those RO-Crates to WorkflowHub, using their RO-Crate Submission API.

See RO-Crate Submission API documentation: https://about.workflowhub.eu/ro-crate-api/

[jmfernandez]

It is going to take a while, as it depends on other developments. Once the code is in place, this requires to integrate the user credentials , and documenting how to obtain a WorkflowHub API token .

[jmfernandez]

There are two possible scenarios:

• Creation of a novel workflow, where the project_id(s) have to be provided.
• Uploading a new release to an existing workflow, where the workflow_id should be provided.