perf: use roaring's range iter to speedup mask_to_offset_ranges (#6871)

The function `mask_to_offset_ranges` is used at scan planning time to
determine which rows to read from the file. This was a bottleneck when
the mask was the result of a zonal index search because the old
implementation materialized all of the offsets only to convert them back
into ranges.

Luckily, roaring recently implemented a range-based iterator. Using this
we can skip the materialization step. On my zonemap benchmark this
doubles the speed of the search and, perhaps more importantly, removes a
penalty I observed when the index is used even on queries that are not
highly selective.

Generated with the assistance of Claude code.

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Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>