Poison the HttpContext after it's disposed by the HttpContextFactory

[davidfowl]

The default HttpContextFactory should poison the HttpContext so that it throws ObjectDisposedException if the feature collection is accessed after the request is over. We'd do this by setting a feature collection that just throws on GetFeature

Related to #3581

cc @Tratcher

[Eilon]

How much of a breaking change is this?

[Tratcher]

How much of a breaking change is this?

A brutal one if you were using it against guidance and somehow managed not to break. Otherwise only a minor one.

[Eilon]

Right 😄 I agree there are no legit cases, but as we know, there are cases where people have been lucky and got away with things.

[rynowak]

If we at least replace the service provider with an empty one, this would go a long way to becoming resilient to memory leaks via execution context.

[davidfowl]

Yep that’s another benefit.