[REVIEW] Add nvtext::porter_stemmer_measure API

[davidwendt]

References #5243

This PR adds nvtext APIs to unblock NVIDIA/cuml#2476
It includes two new APIs ported from the old NVText implementation as referenced in #5243
The algorithm is based on https://tartarus.org/martin/PorterStemmer/def.txt

std::unique_ptr<cudf::column> porter_stemmer_measure(
  cudf::strings_column_view const& strings,
  rmm::mr::device_memory_resource* mr);
std::unique_ptr<cudf::column> is_letter(
  cudf::strings_column_view const& strings,
  letter_type ltype,
  cudf::size_type character_index,  ///---- also a version that takes a column of indices here instead
  rmm::mr::device_memory_resource* mr)

The main difference is since this algorithm only works on English, the aeiou and y characters are hardcoded inside the implementation. The previous NVText version allowed these to be parameters.

This PR will include adding the Python interface as well.

[GPUtester]

Please update the changelog in order to start CI tests.

View the gpuCI docs here.

[davidwendt]

rerun tests

[codecov]

Codecov Report

Merging #5767 into branch-0.15 will increase coverage by 0.33%.
The diff coverage is 100.00%.

@@               Coverage Diff               @@
##           branch-0.15    #5767      +/-   ##
===============================================
+ Coverage        84.08%   84.41%   +0.33%     
===============================================
  Files               80       80              
  Lines            13062    13395     +333     
===============================================
+ Hits             10983    11308     +325     
- Misses            2079     2087       +8     

Impacted Files	Coverage Δ
python/cudf/cudf/core/column/string.py	86.82% <100.00%> (+0.41%)	⬆️
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%)	⬆️
... and 30 more

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[davidwendt]

rerun tests

[ramakrishnap-nv]

LGTM

[ramakrishnap-nv]

Don't merge this as one cpp review is still pending.

[codereport]

This code looks great! And it is such a cool algorithm. Only 1 small change.

[codereport]

Looks great 👍