BUG: read_fwf raise if len colspec doesnt match len names
- [x] closes #40830
- [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
- [x] whatsnew entry

@mzeitlin11 how's this look? > @mzeitlin11 how's this look?

Sorry for delay, this LGTM, caveat that not too familiar with read_fwf, but with all the awesome added test coverage all these paths are exercised thanks @debnathshoham 