add family of generated Samtec HSEC8 PCB card edge footprints

These are the footprints generated by kicad-footprint-generator!809 (merged).

Documentation:

• Footprint: https://suddendocs.samtec.com/prints/hsec8-1xxx-xx-xx-dv-x-xx-footprint.pdf (page 8)
• Socket: https://suddendocs.samtec.com/prints/hsec8-1xxx-xx-xx-dv-x-xx-x-xx-mkt.pdf
• Catalog: https://suddendocs.samtec.com/catalog_english/hsec8_dv.pdf

See also merge request kicad-footprint-generator!809 (merged) which also shows some example footprints etc.

Library:

The footprints are generated into of a new Connector_Samtec_HSEC8.pretty library.

Related socket footprints:

See kicad-footprint-generator!811 (closed) and !2942 (merged).

• [ ] Arcs in KicadModTree are exported in wrong format (kicad-footprint-generator#653 (closed)) generated footprints were upgrade via kicad-cli,
• Wait for kicad-footprint-generator!810 (merged) (kicad-footprint-generator#654 (closed))
• [ ] Wait for kicad-footprint-generator!812 (merged) merged into kicad-footprint-generator!809 (merged)