ENH: Infer integer-na in infer_dtype
- [x] closes #27283
- [x] tests added/passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry

As mentioned in #27335, this PR serves as an infrastructure for future changes in the default int type

@gfyoung  Tests added @jreback Green now @gfyoung ok here? thanks @jiangyue12392 keep em coming! you are tackling non-trivial issues and making very nice PRs!