[Discussion] Use lints via `package:lints`

I believe that we do want to write effective dart code, but this might not be feasible for new learners. Sometimes too many lints can distracting. So I suggest that we use [`package:lints`](https://pub.dev/packages/lints) for our repo, this will cover all of the exercise examples and tests without necessarily forcing learners to use theses lints. We could then manually add exercise directories in `check_formatting` script like so `dartanalyzer.bat --options=.\analysis_options.yaml .\exercises\anagram\lib .\exercises\anagram\test`.