Implement task to save outputs of `IntegrateBlissScanWithoutSaving` to NeXus

For #12 (closed) (#12 (comment 231985) specifically)

I didn't change the API of the existing task SaveNexusPattern1D to not break existing workflows. Instead, I extracted some of its methods into util functions to reuse them in the new task SaveNexusCakeOrStack (input welcomed on the name) EDIT: Renamed SaveNexusIntegrated.

If we can sort out API change problems, I think both tasks could merged in one.