C++ refactoring: High-level to/from_arrow functions for v2.

[jpivarski]

No description provided.

[codecov]

Codecov Report

Merging #1131 (151508c) into main (0b0fb3f) will increase coverage by 1.16%.
The diff coverage is 81.12%.

Impacted Files	Coverage Δ
src/awkward/_v2/forms/bitmaskedform.py	67.94% <ø> (ø)
src/awkward/_v2/forms/bytemaskedform.py	69.01% <ø> (ø)
src/awkward/_v2/forms/indexedform.py	72.00% <ø> (+8.84%)	⬆️
src/awkward/_v2/forms/unmaskedform.py	69.49% <ø> (ø)
src/awkward/_v2/operations/convert/from_arrow.py	57.14% <0.00%> (-22.86%)	⬇️
src/awkward/_v2/operations/convert/to_arrow.py	66.66% <0.00%> (+23.80%)	⬆️
...c/awkward/_v2/operations/convert/to_arrow_table.py	22.22% <0.00%> (-57.78%)	⬇️
src/awkward/_v2/types/numpytype.py	91.80% <ø> (ø)
src/awkward/_v2/operations/convert/to_layout.py	21.87% <10.71%> (-58.13%)	⬇️
src/awkward/_v2/forms/indexedoptionform.py	69.56% <50.00%> (-1.21%)	⬇️
... and 26 more