Add JST XAD, 8-20 Pin, Vertical

[bveenema]

Add 3D models for XAD seriers JST connectors. See pull request in footprints: KiCad/kicad-footprints#2310

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Thanks for creating a pull request to contribute to the KiCad libraries!
Remember you must be the legal owner of the 3D model! Models downloaded from a manufacturers website cannot be accepted.

To speed up integration of your PR, please check the following items as you complete them:

• A screenshot of the model(s) aligned with KiCad footprint(s)
• Source files are contributed on the apropriate location
  • Link to the package3d-source pull request or to the script pull request
• Step model submitted in 1:1 scale
• WRL model submitted in 1:2.54 scale
• 3D model alignment checked against KiCad footprint
• WRL model uses correct material properties
• Geometry check performed on the model

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