Fixes to_layout with allow_records=False and allows single-record writing to Arrow and Parquet

[jpivarski]

No description provided.

[codecov]

Codecov Report

Merging #1456 (1fa2155) into main (edfce38) will increase coverage by 1.27%.
The diff coverage is 59.89%.

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)
...c/awkward/_v2/_connect/rdataframe/to_rdataframe.py	0.00% <0.00%> (ø)
src/awkward/_v2/contents/emptyarray.py	71.91% <ø> (-1.69%)	⬇️
src/awkward/_v2/contents/recordarray.py	82.47% <ø> (+0.97%)	⬆️
src/awkward/_v2/contents/regulararray.py	85.36% <ø> (+0.20%)	⬆️
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%)	⬆️
... and 109 more