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/finished_exercise.rs

@@ -0,0 +1,5 @@
+// fake_exercise
+
+fn main() {
+
+}

tests/fixture/state/info.toml

@@ -0,0 +1,11 @@
+[[exercises]]
+name = "pending_exercise"
+path = "pending_exercise.rs"
+mode = "compile"
+hint = """"""
+
+[[exercises]]
+name = "pending_test_exercise"
+path = "pending_test_exercise.rs"
+mode = "test"
+hint = """"""

tests/fixture/state/pending_test_exercise.rs

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