[ENH] Write out lists of commands when running workflow

[ltirrell]

Would it be possible to write out the list of commands in the order which they'll run, instead of just the command.txt files that are created after each node runs (like the write_graph method )? This feature would be useful for debugging and updating workflows, such as when versions of software are updated. Any file type (json, yaml, plain text) would be fine.

[mgxd]

@ltirrell Possibly, although generally when debugging, it helps to run the workflow using Linear plugin. This runs each node serially, so you can ensure the commands will run in the order you decide. We're also looking into regression testing for our interfaces, which will track version updates and flag interfaces that change