[FR] - New API endpoint for "adding case tags"

[rickenella]

Is your feature request related to a problem? Please describe.
Time-consuming manual addition of a large number of tags

Describe the solution you'd like
For reasons of consistency, it would be very practical if you could fall back on your own internally defined (case) tags.
Therefore, I would suggest adding a new endpoint manage_tags_add to the blueprints.
The corresponding function has already been implemented.

In this sense, it would also be practical to have access to these tags when creating/updating a case.