This supports visit definition from group dimension.

This requires that we call a method on the Instrument class to
get the group_id from the name.

Uses ObservationInfo.observing_day_offset

This allows subclasses to call the parent class even if exposure
is not known.

This allows the codepath to be tested with and without the
offset. Only change a single dataset and move it to a different
day to avoid definition inconsistencies.

This can be used to calculate the observing day offset when
importing old registry YAML files into a butler repository.

…inition

… ingest