dev/sg: 'sg lint' with check.Runner
Created by: bobheadxi
This PR switches sg lint over to the check.Runner framework from https://github.com/sourcegraph/sourcegraph/pull/36556, featuring fancier output and a sizable negative diff 
Closes https://github.com/sourcegraph/sourcegraph/issues/35396
Test plan
go run ./dev/sg lint
