Merge snapshotPivot and snapshot cli commands and support multiple outputs

Not entirely sure I have this right. Will add a cli test once I get a confirmation.
Yes, the only difference is that chord should fail if there are no format, where as that is a valid situation for snapshot. These commands should just be `snapshot` and `chord`, I would be happy to rename now if it isn't too disruptive given that we will have to change downstream code to handle this anyway.