Infer inputs/outputs

When writing a workflow with a step has many options that should be exposed as workflow inputs, it is currently necessary to copy all the parameters to the outer workflow. This is verbose and creates a maintenance problem. I propose a requirement type that instructs the implementation to lift unconnected input and output parameters to the parent workflow.

Start by reviewing the CWL requirement model and the existing workflow input and output behavior. Define the expected semantics for lifting unconnected parameters to the parent workflow, including how completion would be validated in the standard.

Written by the indexing model from the issue text.