feat(tactic/lint): quieter output by default (#3622)
* The behavior of `lint-` hasn't changed.
* `lint` will now suppress the output of successful checks. If everything succeeds, it will print "All linting checks passed!"
* `lint+` behaves like the old `lint`. It prints a confirmation for each test.
Zulip: https://leanprover.zulipchat.com/#narrow/stream/113488-general/topic/quiet.20linter
Co-authored-by: Rob Lewis <rob.y.lewis@gmail.com>
