DauphinPipeline is now backed by the snapshots, meaning that it
can be backed by a serialized format. From this we should be able to
display historical pipeline structures.
Depends on D2315
while this was a good milestone to chase - its unclear whether its "correct" since things like preset are available on a "live" pipeline but not one thats purely backed by snapshot. Maybe this is best respun as a new PipelineReference implementor that is only backed by snapshot