ENH: Add dtype of categories to repr of CategoricalDtype
- [x] closes #52179 (Replace xxxx with the GitHub issue number)
- [x] [Tests added and passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#writing-tests) if fixing a bug or adding a new feature
- [x] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).
- [x] Added [type annotations](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#type-hints) to new arguments/methods/functions.
- [x] Added an entry in the latest `doc/source/whatsnew/vX.X.X.rst` file if fixing a bug or adding a new feature.

```
=================================== FAILURES ===================================
__ [doctest] pandas.core.dtypes.dtypes.CategoricalDtype._from_values_or_dtype __
246             If ``CategoricalDtype``, cannot be used together with
247             `categories` or `ordered`.
248 
249         Returns
250         -------
251         CategoricalDtype
252 
253         Examples
254         --------
255         >>> pd.CategoricalDtype._from_values_or_dtype()
Expected:
    CategoricalDtype(categories=None, ordered=None)
Got:
    CategoricalDtype(categories=None, ordered=None, categories_dtype=None)

/home/runner/work/pandas/pandas/pandas/core/dtypes/dtypes.py:255: DocTestFailure
___ [doctest] pandas.io.json._table_schema.convert_json_field_to_pandas_type ___
167     ------
168     ValueError
169         If the type of the provided field is unknown or currently unsupported
170 
171     Examples
172     --------
173     >>> convert_json_field_to_pandas_type({"name": "an_int", "type": "integer"})
174     'int64'
175 
176     >>> convert_json_field_to_pandas_type(
Expected:
    CategoricalDtype(categories=['a', 'b', 'c'], ordered=True)
Got:
    CategoricalDtype(categories=['a', 'b', 'c'], ordered=True, categories_dtype=object)
``` Thanks @phofl 