bench: add standard window function cases to bounded_window

[neilconway]

Which issue does this PR close?

• Related to BoundedWindowAggExec in Linear mode is slow for many-partitions #23982

Rationale for this change

The bounded_window benchmark only covered aggregate window expressions (count and sum). Window functions such as row_number, rank, lag, lead, and nth_value go through a different code path, for which we had no benchmark coverage.

Add four new benchmark cases:

• linear dense row_number 10000 partitions: per-visit fixed costs on partitions that receive rows in every batch.
• linear sparse row_number 32768 partitions: per-batch work on quiet partitions dominates.
• linear sparse lead 32768 partitions: a non-causal function, whose result for the last buffered row of a partition stays pending until that partition receives another row.
• linear dense rank 10000 partitions: an evaluator that compares ORDER BY values row by row.

Also rename the existing case names to be consistent.

What changes are included in this PR?

• Add 4 new benchmark cases covering standard (non-agg) window functions
• Refactor window benchmark code to enable this
• Rename benchmark case names to be mutually consistent

Are these changes tested?

Yes.

Are there any user-facing changes?

No.