* - Add HP Z420
- Add HP EliteDesk 800 G2 Mini
- Add HP EliteDesk 800 G5 Mini
- Add HP EliteDesk 800 G9 Mini
* adding and declaring images for UniFi Security Gateway Pro
* Delete device-types/HP/HP-EliteDesk-800-G2-Mini.yaml
removing duplicate
* Delete device-types/HP/HP-EliteDesk-800-G5-Mini.yaml
* Delete device-types/HP/HP-EliteDesk-800-G9-Mini.yaml
* Delete device-types/HP/HP-Z420.yaml
* Removing HP images per @harryajc's request.
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Co-authored-by: Harry <Harry@cadby.co.uk>
