dak.firsts should be able to take any axis >= 1 in common case

src/dask_awkward/lib/structure.py

@@ -402,7 +402,7 @@ def firsts(
  behavior: Mapping | None = None,
  attrs: Mapping[str, Any] | None = None,
 ) -> Any:
- if axis == 1:
+ if axis >= 1:
  return map_partitions(
  _FirstsFn(axis=axis, highlevel=highlevel, behavior=behavior, attrs=attrs),
  array,