Added ability to throw exceptions for handling later and to disable the catch-all entry point

Hello,

This pull request does not change any behaviours by default, but it does allow you to have the listener throw exceptions instead of handling the response.

This is useful when using FOSRestBundle which has a much more comprehensive exception controller. It handles setting the correct exception code and in the dev environment shows things such as stack traces. More info is here: https://github.com/FriendsOfSymfony/FOSRestBundle/blob/master/Resources/doc/4-exception-controller-support.md and here an example of the listener: https://github.com/FriendsOfSymfony/FOSRestBundle/blob/master/EventListener/AccessDeniedListener.php

For the same reason, the entry point is not required as this bundle can handle setting the correct response code and message.

The simple config for activating these changes it is:

```
        api:
            pattern:   ^/api
            stateless: true
            lexik_jwt:
                throw_exceptions: true
                create_entry_point: false
```