Disallow Apply parameter usage in Control-block initializers

[jonathan-dilorenzo]

I believe we generally agreed that it is nonsense to use an apply parameter (i.e. one given to a control block on application) in the initialization of that control block, which should happen before the application. Like so:

control ingress(inout Headers h) {
    Headers h1 = h; // Happens before h is passed in?
    ...
}

Let's disallow it in the spec? Notably, it is important that it can still be used in actions e.g. (which I guess wouldn't get instantiated until they're applied with some parameter?) so the language may be a bit subtle.

@ChrisDodd, @KunJeong, @jaehyun1ee, @rcgoodfellow, and @ajwalton for visibility.