Unify behavior of `linters=` argument for `lint()` and friends vs. settings.

[AshesITR]

With CLI usage I meant the linters= argument for lint() and friends.
Since the answer is no, we don't support this shorthand for the config, I agree with your implementation 😊

Originally posted by @AshesITR in #2225 (comment)

This means also supporting, e.g., linters: assignment_linter().