A new class is added which will add meta tags for dates and events.
The class has an interface which allows it to be replaced via DI to
alter behaviour.
Refactor import regarding data handler. We now also need to add a new
column "keywords". We use the new DataHandler approach.
But that approach only covered relations so far. We therefore refactor
that area to be more generic and use that one for new keywords column.
Relates: #10642
The vendor was renamed from `wrm` to `werkraummedia`.
And the namespace vendor was renamed from `Wrm` to `WerkraumMedia`.
That way all references to PHP classes as well as the package name
itself need to be adjusted.
A new PSR-14 event is added that allows to modify the event right before
it is persisted within Destination Data One import.
This for example allows to alter dates, prices, etc.
Improve handling of missing end time in dates.
Destination data provides an attribute "DETAILS_ABGESAGT" to mark an
event as canceled.
We now fetch that info and mark all dates of that event as canceled.
This also contains refactoring of creation of dates within import.
All dates had the same info, and are now created at a single place.
Relates: #9280
That has no effect, the info is just available from model.
This can be used to display a canceled date in a different way, or
render a notice.
Relates: #8092
