TST: Add tests to ensure proper conversion of datetime64/timedelta64/timestamp/duration to and from pyarrow
- [ ] closes #54191 
- [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).


As per [this issue from the pyarrow repository](https://github.com/apache/arrow/issues/33321) there was error in convert_dtypes and pa.table()/pd.to_pandas() in which pyarrow would always return [ns] as unit regardless of associated metadeta. I have added tests to ensure the conversion always preserves associated unit. 

Pyarrow has since fixed and closed the issue in their current main branch (dev version 13.0), and so when it is publicly available the if conditionals mentioned in #54191 can be considered for removal with these tests to ensure functionality remains the same after their removal.  I've fixed the test to match the issue and put it in the proper location, but I'm still having a failing CI "minimum versions" and I can't pinpoint why if anyone could help with that. Might help to merge main again I apologize for all the commits, git is new to me Thanks @Julian048 