DEPR: error_bad_lines and warn_bad_lines for read_csv
- [x] closes #15122
- [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

Summary of contents
    - Adds new on_bad_lines parameter (I found on_bad_lines a more explicit name than bad_lines)
        - This defaults to None at first in order to preserve compatibility, however it should be changed to error in 2.0 after
        error_bad_lines and warn_bad_lines are removed.
    - Cleanup of some C/Python Parser code ( add enum instead of using 2 variables for C and only use on_bad_lines in Python)
Hello @lithomas1! Thanks for updating this PR. We checked the lines you've touched for [PEP 8](https://www.python.org/dev/peps/pep-0008) issues, and found:



















There are currently no PEP 8 issues detected in this Pull Request. Cheers! :beers: 

##### Comment last updated at 2021-05-28 00:23:35 UTC cc @gfyoung if you'd have a look thanks @lithomas1 this was a bear! thanks for sticking with it Thanks for the reviews @jreback. Would it be possible to mention this in the deprecations tracker #30228?(I can't edit it myself.) updated