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.
It not really clear, there are definitely other cases where they are relevant that is not pivot - but it is fairly dependent on the operation. 

Also, the `tombstone` is mis-labelled. It is really a `missing value` not a tombstone, it would be good to rename this while we are here.