Log shipment state transitions to the order activity stream

We needed the same functionality so I created a patch

we need to put this logic in a different event subscriber, that is registered conditionally (i.e only when the commerce_log module is installed), otherwise this logic would crash.

Additionally, we need tests coverage for this logic.

following our Slack discussion, CommerceShippingServiceProvider needs to register a new subscriber, only if commerce_log is enabled.

The subscriber can be called ShipmentLogSubscriber.

Also, let's not hardcode the link to the shipment in the log template but instead pass a {{ shipment_url}} or something.

Note that we need a Kernel test asserting that the log messages are correctly generated (See OrderIntegrationTest under commerce_log for an example).

Let's call it LogIntegrationTest.

Thank you very much for your time. I am afraid I do not have time right now to do the test. But I will try as soon as I can.

Sorry forgot to import class

Relative path fix

@thetwentyseven would you mind creating the final fix as MR? And still needs tests.

I have created MR from the last patch and also have added tests.

The "PHPUnit" pipeline job failed because of FunctionalJavascript tests, the new ShipmentLogSubscriberTest was passed successfully