Messenger integration

This bundle provides a middleware for the symfony/messenger component (from version 4.3) which handles starting/committing/rolling back a transaction when sending a command to the bus.

Here is an example configuration on how to use it:

# app/config/messenger.yaml

framework:
    messenger:
        buses:
            command.bus:
                middleware:
                    - my_eventstore_transaction_middleware

services:
    my_eventstore_transaction_middleware:
        class: Prooph\Bundle\EventStore\Messenger\EventStoreTransactionMiddleware
        arguments:
            - '[@my_transactional_event_store](https://github.com/my_transactional_event_store)'