add Connector_Samtec_HSEC8.kicad_sym Library (generated symbols with pins grouped like Footprints)

The Samtec HSEC8 Card Edge Connector has (for most pin-count-versions) a polarization nodge. For improved clarity between schematics and layout having this gap also visible in the connector symbol is a good thing (at least for my opinion).

Related Footprints:

• Sockets: kicad-footprint-generator!833 (merged) kicad-footprints!2942 (merged)
• Card edges: kicad-footprint-generator!809 (merged) kicad-footprints!2941 (merged)

Generator script:

This footprints have been generated the connector generator script kicad-library-utils!447 (merged)

Screenshots:

• Example of 2 symbols with different pin count:
  
• Related footprints: