For the matcher let's keep a `RequestMatcherInterface` in the `onKernelRequest`

But in configuration it will now be:

```
user_context:
     matcher_id: my_request_matcher_id
```

And we don't use the implementation of Symfony.
Instead the bundle provides a basic implementation with a match on HEAD + Special header
And ezPublish just need to implement it's own request matcher for their vcl.

What do you think @lolautruche @dbu ?

> did we not do the exact same check in the onKernelRequest already? can we not keep that information? or will that mess up with internal requests and we would need to check if its the MASTER request?

Yes let's add also a check on MASTER request as it makes no sense in sub request.

But i prefer to keep this check in the two method, as maybe we can have a listener before which send a response before calling this listener and "caching" this value will make the class state-full :/