Fix strings strip() to accept only str Scalar for to_strip parameter

[davidwendt]

Closes #10591

Ensures to_strip parameter is a str type when converting it to cudf.Scalar. It will now through a TypeError as follows

    libstrings.strip(self._column, cudf.Scalar(to_strip, "str"))
  File "/conda/envs/rapids/lib/python3.8/site-packages/cudf-22.6.0a0+96.g0aef0c1c3e.dirty-py3.8-linux-x86_64.egg/cudf/core/scalar.py", line 78, in __init__
    self._host_value, self._host_dtype = self._preprocess_host_value(
  File "/conda/envs/rapids/lib/python3.8/site-packages/cudf-22.6.0a0+96.g0aef0c1c3e.dirty-py3.8-linux-x86_64.egg/cudf/core/scalar.py", line 128, in _preprocess_host_value
    raise TypeError("Lists may not be cast to a different dtype")
TypeError: Lists may not be cast to a different dtype

This will also prevent the sticky CUDA error.

Also, added the str parameter to other cudf.Scalar calls where only strings are supported as well.

[charlesbluca]

Should we add test(s) for passing the incorrect input type for some of these methods?

[davidwendt]

Should we add test(s) for passing the incorrect input type for some of these methods?

Yes. I think that is a good idea.

[codecov]

Codecov Report

Merging #10597 (2479078) into branch-22.06 (0aef0c1) will increase coverage by 0.02%.
The diff coverage is n/a.

@@               Coverage Diff                @@
##           branch-22.06   #10597      +/-   ##
================================================
+ Coverage         86.29%   86.31%   +0.02%     
================================================
  Files               140      140              
  Lines             22255    22255              
================================================
+ Hits              19205    19210       +5     
+ Misses             3050     3045       -5     

Impacted Files	Coverage Δ
python/cudf/cudf/core/column/string.py	89.10% <ø> (+0.12%)	⬆️
python/cudf/cudf/datasets.py	97.56% <0.00%> (ø)
python/cudf/cudf/utils/cudautils.py	59.83% <0.00%> (ø)
python/cudf/cudf/core/udf/templates.py	100.00% <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/cudf/cudf/core/udf/row_function.py	100.00% <0.00%> (ø)
python/cudf/cudf/core/udf/scalar_function.py	100.00% <0.00%> (ø)
python/cudf/cudf/core/groupby/groupby.py	91.72% <0.00%> (+0.22%)	⬆️
... and 3 more

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[galipremsagar]

@gpucibot merge