Ensure we pass an url in every analytics calls

For now, in GA, all sources (nuxeo.com, etc.) are using the same account. We need to be able to split analytics from Connect to other websites.

One easy approach for GA users is to filtering out by URL. And for now, we are only sending an URL parameter from frontend events.

We should add a url parameter in every event send even from the server-side. Relying on nuxeo.url property as a fallback if it cannot be more precise

Because of lack of HF release; we need to first fix in Segment.IO addon (NXP-28811); then overriding org.nuxeo.segment.io.listener.SegmentIOAsyncListener listener in order to have the changes in our code.