Export nested lists (and optional import)

[inukshuk]

• Export nested lists (using nested arrays?). For top-level lists the nested array should be optional to make sure we still support the current format (simple list of strings).
• Create lists and add items accordingly on import. This is not necessarily what we want to do by default though, so we should probably hide it behind a preference. (Lists with the same name are not necessarily the same across projects!)

Besides importing lists, this would allow for an import plugin that translates a folder hierarchy to nested lists.

See #693

[MHindermann]

Is there a timeline for this feature? I am at the moment working with a project that uses hierarchical lists to define an archival order and wants to do some data enrichment on the Tropy export JSON-LD (e.g., add transcriptions to photos as notes via script), but the lists getting lost on the reimport is of course an issue.

[inukshuk]

There's no timeline yet, but if somebody's using it, we typically try to make it a priority.

Export should be trivial to add, I'm a little concerned about import though. Currently, lists are not imported at all. This is mainly because you can import items into a list specifically; I think we'd have to add a separate import option (or a plugin?) that creates missing lists and adds the items right away.

@flachware @caro401 what do you think?

[flachware]

A separate import option sounds good to me.