Add Example Database for Demos to Container

[RobertRosca]

#142 added a container which can be used to start the DAMNIT GUI with a command like:

docker run --rm -it --net=host -e DISPLAY=:0 ghcr.io/european-xfel/damnit:edge

Which is fully sandboxed and has no data from the host mounted into it.

It would be nice to have, either in the container or just in the repository in general, a small example directory with a context file and database (if it's small, just included in the repo/image, or generated with mock data) which could then be the default directory when starting up the container image.

[JamesWrigley]

We could generate a database with --mock when building the image:

amore-proto reprocess --mock $(seq 1 50)

I often do that for testing. --mock will create a MagicMock object and pass it to the variables instead of a RunData object, though the mock object only mocks certain parts of a DataCollection to work with internals of Extractor, so a context file shouldn't actually use the mock object.