DEPR: Deprecate mangle_dupe_cols
- [X] xref #47718, 48037
- [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.

Deprecating `mangle_dupe_cols`, which was never implemented, and will be replaced by a new standard argument to allow change the format of the renamed columns.
Thanks @datapythonista  @datapythonista do you have bandwidth to enforce this deprecation? I could take this as well next week