Ability to inject FileCacheReader

[umpirsky]

Reading annotations using Doctrine\Common\Annotations\AnnotationReader is not the most optimal way as it does not use annotation cache.

After this fix, service can be override to use Doctrine\Common\Annotations\FileCacheReader:

kayue_wordpress.table_prefix.subscriber:
    class: %kayue_wordpress.table_prefix.subscriber.class%
    arguments:
        - %kayue_wordpress.table_prefix%
        - @annotation_reader
    tags:
        - { name: doctrine.event_subscriber }

[kayue]

Thanks @umpirsky