Annotations: add types if possible
# Feature Request
## Description
Our annotations have (virtually) different types like "place", "person", or "motif".
The actual output of the annotations is agnostic to that, but for filtering the annotations a key to distinguish them would come in handy.
## User Story
As developer of the viewer I need a means to distinguish the annotations in order to display the correct annotations.
As a user I want to display all instances of a certain annotation type (e.g. "person"s) on a page.
/cc [Mathias Göbel](https://gitlab.gwdg.de/mgoebel), [Frank Schneider](https://gitlab.gwdg.de/schneider210), [Michelle Weidling](https://gitlab.gwdg.de/mrodzis)
issue