Stop raising in read_csv when header row contains only empty cells
- [x] closes #13054
- [x] tests added / passed
- [x] Ensure all linting tests pass, see [here](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit) for how to run them
- [x] whatsnew entry

If ok with the change in general, I would suggest deprecating and changing in 2.0
why deprecating and not implementing the unamed case? Was not sure if people relied on this behavior. If you think is ok to immediately stop raising, will implement that @jreback this immediately changes from raising to returning only Unnamed columns thanks @phofl 