At next major CLI version, remove id from workflow.yaml #1595

The id field saved to workflow.yaml is misleading in its importance. Really the id is just a local alias, derived by default from the name.

The next major CLI version should stop writing it to file.

The only reason to hesitate is that older CLI versions pulling from a repo created with a new CLI will start breaking if workflow.id is omitted. I think this is a tiny edge case but I'm not sure it's worth taking the risk for what is basically a tidyup.