Some imagemagick-versions (I tested Ubuntu 22.04 and debian bullseye)
always loose exif data when converting from jpg to webp. So this made
our CI fail now, but even if it wasn't failing before, some pods always
had and have versions which might loose the information anyway. So
having a setting to keep exif information is kinda pointless, if we
can't guarantee that the information isn't lost. Also, diaspora isn't a
photo sharing platform and we don't display exif information anywhere,
so I think we should just always strip exif data (which was already the
default before), as we don't need them.
This commit introduces changes to the user data export archive format.
This extends data set which is included in the archive. This data can be
then imported to other pods when this feature is implemented.
Also the commit adds the archive format json schema. ATM it is used in
automatic tests only, but in future it will also be used to validate
incoming archives.
