ENH: allow attrs to be propagated via pd.concat
- [x] closes #41828
- [x] tests added / passed
- [x] Ensure all linting tests pass, see [here](https://pandas.pydata.org/pandas-docs/dev/development/contributing.html#code-standards) for how to run them
- [ ] whatsnew entry

@TomAugspurger @lithomas1 I have made a fix to this issue and I wonder if do you mind have a review, please? I will add the whatsnew when this PR is about to be merged.