Incorporate "rest" and "openapi" functions into "openapi"

What would you like to be added: Since we introduced rest operation type as a shortcut to embed the OpenAPI definition within a workflow, instead of having a different type we can incorporate it into the openapi type.

In practice, we will have a function that can link to an OpenAPI file or have the operation described directly via the paths OpenAPI Schema object.

Why is this needed: See the discussion here: https://github.com/serverlessworkflow/specification/discussions/817

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.