[REVIEW] Fix issue with extracting nested column data & dtype preservation

[galipremsagar]

Description

This PR:
Fixes: #11670

• Fixes: [BUG] Extracting a nested list-host-scalar throws error #11670, by correctly generating the column_metadata for nested scenarios.
• Also fixes an issue with dtype mismatch after updating children in a ListColumn. See the pytest below.

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.

[galipremsagar]

The current branch-22.10 issue can be seen in this error:

(Pdb) assert_eq(df.a.dtype, actual.a.dtype)
*** AssertionError: 
Items are not equal:
 ACTUAL: StructDtype({'Domain': StructDtype({'Id': StructDtype({'Name': dtype('O'), 'Value': dtype('O')}), 'Name': dtype('O')}), 'Duration': dtype('int64'), 'Offset': dtype('int64'), 'Resource': ListDtype(StructDtype({'Name': dtype('O'), 'Value': dtype('O')})), 'StreamId': dtype('O')})
 DESIRED: StructDtype({'Domain': StructDtype({'Id': StructDtype({'Name': dtype('O'), 'Value': dtype('O')}), 'Name': dtype('O')}), 'Duration': dtype('int64'), 'Offset': dtype('int64'), 'Resource': ListDtype(StructDtype({'0': dtype('O'), '1': dtype('O')})), 'StreamId': dtype('O')})

[codecov]

Codecov Report

Base: 86.39% // Head: 86.41% // Increases project coverage by +0.02% 🎉

Coverage data is based on head (f6da734) compared to base (9f8db66).
Patch coverage: 100.00% of modified lines in pull request are covered.

❗ Current head f6da734 differs from pull request most recent head d12acd9. Consider uploading reports for the commit d12acd9 to get more accurate results

Additional details and impacted files

@@               Coverage Diff                @@
##           branch-22.10   #11671      +/-   ##
================================================
+ Coverage         86.39%   86.41%   +0.02%     
================================================
  Files               145      145              
  Lines             23005    23009       +4     
================================================
+ Hits              19875    19884       +9     
+ Misses             3130     3125       -5     

Impacted Files	Coverage Δ
python/cudf/cudf/core/column/column.py	88.62% <100.00%> (ø)
python/cudf/cudf/core/column/lists.py	93.75% <100.00%> (+1.10%)	⬆️
python/cudf/cudf/core/column/numerical.py	95.61% <0.00%> (-0.30%)	⬇️
python/cudf/cudf/core/dataframe.py	93.77% <0.00%> (+0.04%)	⬆️
python/cudf/cudf/core/column/string.py	88.53% <0.00%> (+0.12%)	⬆️
python/cudf/cudf/core/groupby/groupby.py	91.12% <0.00%> (+0.21%)	⬆️
python/cudf/cudf/core/tools/datetimes.py	84.49% <0.00%> (+0.30%)	⬆️

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[wence-]

Overall looks good, with minor queries about some aspects, and then a more general question about whether the API of interop.to_arrow is the most natural one.

[wence-]

Thanks!

[galipremsagar]

@gpucibot merge