Compute list/map cardinality from offsets #25078

Is your feature request related to a problem or challenge?

We can compute cardinality by looking at the offsets in the GenericListArray. The current implementation creates a new array slice for every row and then fetches the length of the slice, which involves a lot of unnecessary per-row overhead.

For lists whose elements are scalar types, this is straightforward. For lists whose elements are themselves lists, this is possible but would be more complex (#25085)

Describe the solution you'd like

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Additional context

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