Backport PR #60321: TST (string dtype): resolve all xfails in IO pars…

[WillAyd]

Backport of #60321

[WillAyd]

Hmm not sure how to fix the failing test here. There's a lot of mutability going on in the CSV parser...but I can trace things back to base_parser.py:510 which calls:

index = ensure_index_from_sequences(arrays, names)

At that point in time, arrays has the right data with the proper dtype:

[array(['01'], dtype=object)]

but the Index constructor seems to force that to str, whereas the test expects object to be maintained.

@jorisvandenbossche any thoughts on this one?

[jorisvandenbossche]

I have a local fix (have to include changes from #59316 I think), will clean up and push tomorrow