[FEA] Add an option to enable pandas debugging mode in cudf.pandas fast path

[Matt711]

Is your feature request related to a problem? Please describe.
We would like a feature that allows us to debug incorrect results in the cudf.pandas fast path. This would allow us to find functions that are supported in cudf and are not matching results from pandas. Overall, it would make debugging incorrect results easier as more third-party pandas libraries use cudf.pandas.

Describe the solution you'd like
The feature would be an option to enable "pandas debugging mode" in _fast_slow_function_call. First we would check if the fast path runs without any problems. If so, we would check if the pandas debugging mode was on and then run the slow path. Finally, we compare the results and return a warning if the results aren't the same. We would return a warning and not an error because there are some results we expect to differ like join and groupby.

[Matt711]

Closing this issue as its covered by #14975