build or buy: Avatars

[matmair]

As part of #9116 I added the UI foundations for (user) avatars. Now the question regarding handling those is if we use a library or build the mechanisms ourself.
I am unsure as there are libraries that look quite promising:https://django-avatar.readthedocs.io
On the other hand, we add a dependency for a thing that could be a few lines in the profile endpoint.

Interested in your viewpoints on this. I would volunteer to handle it either way.

[SergeoLacruz]

Depends on how much work a self written solution is. I cannot judge this.
To me it seems that the part picture or company picture feature is the same.