Enhancements for IWC

`workflow_metadata_init`: Should generate readme template (ideally with inputs and outputs listed as we do manually now), changelog, inject a release field

`workflow_iwc_init`: Combines all of the actions we want authors to execute, so `workflow_test_init` ,`workflow_metadata_init`, `dockstore_init`. Maybe include `planemo workflow_lint` ?

`workflow_best_practices`: Check the actual best practices API, as opposed to the approximation we have in `planemo workflow_lint`