Add Benchmark Rollup

Added

• Benchmark taxonomy rollup on create_benchmark / update_benchmark. You can now set a benchmark's class taxonomy when creating it via rollup_groups, an existing allowed_label_matches_id, or class_agnostic=True (the three are mutually exclusive). update_benchmark accepts the same fields to set/replace a draft's rollups (pass allowed_label_matches_id=None to clear it). Benchmark now surfaces allowed_label_matches_id and class_agnostic on read.

  benchmark = client.create_benchmark(
      "city-streets-v1",
      slice_id="slc_...",
      rollup_groups=[RollupGroup("vehicle", ["car", "truck"])],
  )

Fixed

• Benchmark taxonomy exclusivity now counts every field that will be sent. update_benchmark(..., rollup_groups=..., allowed_label_matches_id=None) and class_agnostic=False mixed with another taxonomy used to pass the client check and then get rejected by the backend.