add family of generated Samtec HSEC8-DV socket footprints

These are the footprints generated by kicad-footprint-generator!833 (merged).

Documentation:

• Footprint: https://suddendocs.samtec.com/prints/hsec8-1xxx-xx-xx-dv-x-xx-footprint.pdf (pages 1 and 2)
• 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

KLC warnings:

• F7.4 Pad requirements for THT footprints:
  the -WT and -BL variants of the sockets have a weld-tab which has to be soldered paste-in-hole technology. Therefore the F.Paste layer is part of the THT weld-tab-pads.

Library:

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

Related card edge footprints:

See kicad-footprint-generator!809 (merged) and !2941 (merged).