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 categories to be
assigned to an event.
The event itself (including already existing categories) as well as the
list of categories to be used after import are available.
It is possible to change the categories to be assigned, e.g. keep some
of the existing categories.
That way it is possible for installations to add custom categories to
events.
Relates: #10623
Extbase Category repository was used, while custom Category instances
were expected.
The repository didn't inherit from Extbase Repository and therefore
didn't provide expected findByUid method.
