fix(run): makes run never prompt

`watch` and `verify` do prompt the user to actively move to the
next exercise. This change fixes `run` to never prompt. Previously
it was inconsistent between "test" and "compile" exercises.

BREAKING CHANGE: we again change the behavior of the `run` command

tests/fixture/state/pending_test_exercise.rs

@@ -0,0 +1,4 @@
+// I AM NOT DONE
+
+#[test]
+fn it_works() {}