C++ refactoring: ak.num

[ioanaif]

No description provided.

[codecov]

Codecov Report

Merging #1226 (d8f24c5) into main (0a0e9be) will decrease coverage by 1.09%.
The diff coverage is 78.24%.

Impacted Files	Coverage Δ
src/awkward/_v2/contents/bytemaskedarray.py	79.43% <ø> (+0.28%)	⬆️
src/awkward/_v2/contents/emptyarray.py	69.54% <ø> (ø)
src/awkward/_v2/contents/content.py	81.74% <23.07%> (-1.45%)	⬇️
src/awkward/_v2/_typetracer.py	68.94% <33.33%> (-0.25%)	⬇️
src/awkward/_v2/highlevel.py	64.62% <33.33%> (-0.37%)	⬇️
src/awkward/_v2/_slicing.py	83.79% <75.47%> (-2.48%)	⬇️
src/awkward/_v2/_util.py	81.99% <80.00%> (-0.10%)	⬇️
src/awkward/_v2/contents/regulararray.py	82.66% <80.00%> (+0.07%)	⬆️
src/awkward/_v2/operations/structure/ak_where.py	87.50% <86.11%> (+7.50%)	⬆️
src/awkward/_v2/operations/structure/ak_ravel.py	91.66% <87.50%> (+11.66%)	⬆️
... and 21 more

[jpivarski]

Everything here looks good! I'll merge it.