Combine multiple selections into the same batch size in skip_records

[Ted-Jiang]

The skip records API added to the ArrayReader trait as part of #1998 does not provide a way to combine multiple selections into the same batch. This is unfortunate as columnar query engines will often want consistently large RecordBatch so that any dispatch overheads can be amortised over many rows. Whilst it could concatenate batches together, e.g. DataFusion's CoalesceBatchesExec, it would be more efficient to do this directly on read and eliminate an additional copy.

Originally posted by @tustvold in #2197 (comment)