Handle duplicate workflow step names

[fractaledmind]

Imagine having a job like this:

with_acidic_workflow persisting: { } do |workflow|
  workflow.step :no_op, awaits: [PreprocessingJob.new]
  workflow.step :do_thing
  workflow.step :no_op, awaits: :post_process_if_necessary
end

Currently, workflow steps with the same name will conflict and only one will be set in the Run#workflow hash. This is a foot-gun. We don't like foot-guns. We should resolve