Remove array type hint from GetResponseForControllerResultEvent::setControllerResult()

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| License       | MIT

I don't see a good reason to limit responses to arrays. The method was introduced in 2.2, so there is no real BC break.