Support proper motion and parallax for targets in pfsDesign files

As discussed on the #obsproc slack channel on 2022-10-02, we need to support fast-moving objects for PFS.

The GUIDESTARS table does have proper motion support as we were worried about extra-Galactic sources, but we didn't think about target stars.

Please add epoch, pmRa, pmDec, parallax to the DESIGN table, with definitions identical to those for the guidestars.

When designing plates we need to pay attention to these columns, but the exact observing date shouldn't matter (as we finalise the cobra positions just before observing).