Add Harwin S1621 SMD jumper

Datasheet: https://cdn.harwin.com/pdfs/S1621R.pdf

Drawing:

Footprint:

Fit-up with mfr STEP (orthographic top-down and oblique):

Design choices:

• 0.5mm y-courtyard chosen to give the recommended 3.3mm pitch side-by-side and to allow slight misplacement on the provided pads.