Allow NumPy arrays in CppStatements; fix row_groups in single-file from_parquet.

[jpivarski]

Somehow, I forgot to check this in earlier.

[codecov]

Codecov Report

Merging #1376 (4ae8bae) into main (b2fd2be) will decrease coverage by 0.20%.
The diff coverage is 51.52%.

Impacted Files	Coverage Δ
src/awkward/_v2/_connect/cling.py	0.00% <0.00%> (ø)
src/awkward/_v2/_lookup.py	97.50% <0.00%> (ø)
src/awkward/_v2/_prettyprint.py	66.09% <0.00%> (+2.29%)	⬆️
src/awkward/_v2/_typetracer.py	69.14% <0.00%> (ø)
src/awkward/_v2/identifier.py	55.69% <0.00%> (ø)
src/awkward/_v2/operations/convert/ak_from_jax.py	75.00% <0.00%> (ø)
src/awkward/_v2/operations/convert/ak_to_jax.py	75.00% <0.00%> (ø)
src/awkward/_v2/operations/io/ak_from_parquet.py	75.00% <0.00%> (ø)
src/awkward/_v2/operations/io/ak_to_parquet.py	75.00% <0.00%> (ø)
src/awkward/_v2/operations/structure/ak_firsts.py	75.00% <0.00%> (ø)
... and 147 more