[FEA] Use more performant dtype introspection utility in select_dtypes

[mroeschke]

xref #18141 (comment)

select_dtypes has a internal dtype introspection function cudf_dtype_from_pydata_dtype to "normalize" include= and exclude= dtypes

cudf/python/cudf/cudf/core/dataframe.py

Line 6857 in 8e4408c

def cudf_dtype_from_pydata_dtype(dtype):

This function is a bit more expensive than other dtype checking functions in cudf and has a drastic performance difference when normalizing string-specified types vs dtype objects. At minimum some caching should be implemented to not incur such a performance penalty between the two