Add current sensors
Continuing from the discussion at https://github.com/KiCad/Housings_SSOP.pretty/pull/49, I added all four AKM current sensors (some slight naming differences) and and the Allegro current sensor footprints too. Once this is merged I can remove the Allegro ones from the THT TO/SOT repo if that matters. Or maybe just leave them since this will take care of things with v5?