Passing behaviour in ak._v2 functions

[ioanaif]

No description provided.

[codecov]

Codecov Report

Merging #1415 (fc7f9ec) into main (edfce38) will decrease coverage by 0.03%.
The diff coverage is 47.23%.

Impacted Files	Coverage Δ
src/awkward/_v2/_connect/cuda/__init__.py	0.00% <0.00%> (ø)
src/awkward/_v2/_connect/jax/__init__.py	0.00% <0.00%> (ø)
src/awkward/_v2/contents/indexedarray.py	62.32% <0.00%> (+0.43%)	⬆️
src/awkward/_v2/operations/convert/ak_from_cupy.py	50.00% <0.00%> (+23.33%)	⬆️
src/awkward/_v2/operations/convert/ak_from_iter.py	93.75% <ø> (ø)
src/awkward/_v2/operations/convert/ak_from_jax.py	50.00% <0.00%> (-25.00%)	⬇️
src/awkward/_v2/operations/convert/ak_to_cupy.py	33.33% <0.00%> (+23.95%)	⬆️
src/awkward/_v2/operations/convert/ak_to_jax.py	33.33% <0.00%> (-41.67%)	⬇️
src/awkward/_v2/operations/describe/ak_backend.py	10.00% <0.00%> (-2.50%)	⬇️
...wkward/_v2/operations/structure/ak_argcartesian.py	78.94% <ø> (ø)
... and 23 more

[jpivarski]

Nice! I did a sweep, just to check that every appearance of a highlevel variable has a corresponding behavior variable, and that all ak._v2._util.behavior_of passes in the given behavior if it has one.

Along the way, I found out that none of the reducers have highlevel or behavior. Perhaps they should, but at least this is consistent.