Add properties.published_by to notification message

[antje-s]

We had problems with notifcations that are republished by GCs and also have set cache="false".
In these cases, it is not possible to determine who republished the notification via the download link value. In the event of notification format errors, no suitable contact person can be found.
Initial value could be center-id of the originator and then be replaced by the GCs with their center-id.

If we always carry this value with us, we can also determine which GCs republished which origin notification. This could be a useful information in the pre-operational phase.

To be discussed during our next TT-WISMD meeting if useful/needed...

[tomkralidis]

TT-WISMD 2024-03-25:

• allowing consumers subscribing to 'cache'd data may or may not be aware that a given organization has set their notification to cache: false
• what is the value of differentiating between origin and cache then?
• may be difficult for users to "search" for topics, not knowing what is routed where
• needs more thought
• origin will have more data notifications than cache