Calculating extent_points

_extent_points_ are an extra attribute which we might only need when we ingest to OSDU. Since this requires a bit of thought, and and the easiest way of calculating extents accounting for rotation would be to derive it from the bulk data, we are not adding it for the MVP. We may add it in the future, so should we remove the column for now or keep it (and will have 'nulls' everywhere?)