Consider disallowing use of `use function...`

In line with https://github.com/humanmade/Engineering/pull/143, I propose that we add a rule dis-allowing the use of `use function`.

As noted by Joe in https://github.com/humanmade/Engineering/pull/143#issuecomment-560330827, this will break linting for several current projects. I personally feel that this is worth it as the rule can be ignored on current projects and it will enforce properly on all new projects.