[Hold] Unstructured API: templated workflows and on-demand jobs

[Paul-Cornell]

Ready for review prior to release.

See:

• How to list available workflow templates programmatically: https://unstructured-53-doc-57-on-demand-api.mintlify.app/api-reference/workflow/workflows#list-workflow-templates
• How to get information about an individual workflow template programmatically: https://unstructured-53-doc-57-on-demand-api.mintlify.app/api-reference/workflow/workflows#get-a-workflow-template
• How to create a long-lasting workflow that uses a workflow template: https://unstructured-53-doc-57-on-demand-api.mintlify.app/api-reference/workflow/workflows#create-a-workflow (scroll down in this section to discussion of <workflow-type>)
• Usage note about on-demand jobs, added to existing "run workflow" operation reference: https://unstructured-53-doc-57-on-demand-api.mintlify.app/api-reference/workflow/overview#run-a-workflow
• How to run on-demand jobs programmatically: https://unstructured-53-doc-57-on-demand-api.mintlify.app/api-reference/workflow/overview#run-an-on-demand-job

Only curl and Postman details are currently available. Awaiting Python SDK details, which will likely be a follow-on PR.