[REVIEW] Add cudf::lists::extract_list_element API

[davidwendt]

Closes #5742

New API to extract elements from a lists column into a new column

std::unique_ptr<column> extract_list_element(
  lists_column_view const& lists_column,
  size_type index,
  rmm::mr::device_memory_resource* mr);

The index is used to extract individual elements from each of the lists components to build a new column as described in #5742

[codecov]

Codecov Report

Merging #5753 into branch-0.15 will increase coverage by 0.33%.
The diff coverage is n/a.

@@               Coverage Diff               @@
##           branch-0.15    #5753      +/-   ##
===============================================
+ Coverage        84.06%   84.40%   +0.33%     
===============================================
  Files               80       80              
  Lines            13066    13381     +315     
===============================================
+ Hits             10984    11294     +310     
- Misses            2082     2087       +5     

Impacted Files	Coverage Δ
python/cudf/cudf/io/feather.py	100.00% <0.00%> (ø)
python/cudf/cudf/comm/serialize.py	0.00% <0.00%> (ø)
python/custreamz/custreamz/_version.py	0.00% <0.00%> (ø)
python/dask_cudf/dask_cudf/_version.py	0.00% <0.00%> (ø)
python/dask_cudf/dask_cudf/io/tests/test_orc.py	100.00% <0.00%> (ø)
python/dask_cudf/dask_cudf/io/tests/test_json.py	100.00% <0.00%> (ø)
...ython/dask_cudf/dask_cudf/io/tests/test_parquet.py	100.00% <0.00%> (ø)
python/cudf/cudf/utils/applyutils.py	98.75% <0.00%> (+0.02%)	⬆️
python/cudf/cudf/core/join/join.py	92.41% <0.00%> (+0.03%)	⬆️
...ython/custreamz/custreamz/tests/test_dataframes.py	98.80% <0.00%> (+0.03%)	⬆️
... and 29 more

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[kkraus14]

CMake lgtm

[vuule]

Looks good, just one minor suggestion

[davidwendt]

rerun tests