ILogStuff - enabling logging from `connection_impl` and transports

Note that a side effect of this change is that we now will be able to raise events from transports since transports now will have a (smart) pointer to the connection_impl instance.
For unit tests these two don't matter. `transport` needs a back pointer to the `connection_impl` but at the non-unit test level `connect` is invoked by the `connection_impl` instance which will result in using the same value. In unit test we call `connect` explicitly and therefore have to provide a url which again does not matter since we are mocking the network and don't use/check these urls at all.