Change expect_strings_empty into expect_column_empty libcudf test utility

[davidwendt]

Description

Moves the cudf::test::expect_strings_empty utility from cpp/tests/strings to more generic function cudf::test::expect_column_empty

Reference #11734

Checklist

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

[codecov]

Codecov Report

Base: 87.40% // Head: 87.48% // Increases project coverage by +0.07% 🎉

Coverage data is based on head (6876f16) compared to base (f72c4ce).
Patch coverage: 84.03% of modified lines in pull request are covered.

Additional details and impacted files

@@               Coverage Diff                @@
##           branch-22.12   #11873      +/-   ##
================================================
+ Coverage         87.40%   87.48%   +0.07%     
================================================
  Files               133      133              
  Lines             21833    21866      +33     
================================================
+ Hits              19084    19130      +46     
+ Misses             2749     2736      -13     

Impacted Files	Coverage Δ
python/cudf/cudf/core/udf/__init__.py	50.00% <ø> (ø)
python/cudf/cudf/utils/ioutils.py	79.47% <ø> (ø)
...thon/dask_cudf/dask_cudf/tests/test_distributed.py	18.86% <ø> (+4.94%)	⬆️
python/cudf/cudf/core/_base_index.py	82.20% <43.75%> (-3.35%)	⬇️
python/cudf/cudf/io/text.py	91.66% <66.66%> (-8.34%)	⬇️
python/strings_udf/strings_udf/__init__.py	86.27% <76.00%> (-10.61%)	⬇️
python/cudf/cudf/core/index.py	92.91% <95.08%> (+0.27%)	⬆️
python/cudf/cudf/__init__.py	90.69% <100.00%> (ø)
python/cudf/cudf/core/column/categorical.py	89.34% <100.00%> (ø)
python/cudf/cudf/core/scalar.py	90.52% <100.00%> (+1.25%)	⬆️
... and 6 more

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

☔ View full report at Codecov.
📢 Do you have feedback about the report comment? Let us know in this issue.

[bdice]

Everything looks great!

[davidwendt]

@gpucibot merge