fix: ak.from_iter should interpret top-level tuples as ak.Array (v1 and v2).

[jpivarski]

This was accidentally the behavior before #1614, and some libraries assumed it. Now the policy is as described in test_1642-from_iter-of-tuples (both v1 and v2).

[codecov]

Codecov Report

Merging #1642 (7192d68) into main (9e17f29) will increase coverage by 0.53%.
The diff coverage is 67.75%.

Additional details and impacted files

Impacted Files	Coverage Δ
src/awkward/_v2/_connect/cuda/__init__.py	0.00% <0.00%> (ø)
src/awkward/_v2/_connect/numexpr.py	88.40% <0.00%> (ø)
src/awkward/_v2/_connect/pyarrow.py	88.46% <0.00%> (ø)
...awkward/_v2/_connect/rdataframe/from_rdataframe.py	0.00% <0.00%> (ø)
src/awkward/_v2/_lookup.py	98.68% <ø> (+1.17%)	⬆️
src/awkward/_v2/numba.py	93.47% <0.00%> (ø)
src/awkward/_v2/operations/ak_from_avro_file.py	66.66% <0.00%> (ø)
src/awkward/_v2/operations/ak_local_index.py	100.00% <ø> (ø)
src/awkward/_v2/operations/ak_max.py	87.09% <ø> (ø)
src/awkward/_v2/operations/ak_min.py	87.09% <ø> (ø)
... and 59 more

[agoose77]

Huh, good catch @jpivarski. I hadn't fully appreciated that tuple was special cased in ArrayBuilder. Thanks for the fix.