Add ubiquiti unifi security gateway pro images (#2685)

* - 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>

device-types/Ubiquiti/USG-PRO-4.yaml

@@ -11,6 +11,8 @@ comments: |
   (*, see datasheet) The USG-PRO-4 WAN port, as a result of being a combination SFP/GigE port, is a pure 1Gbps port - it is incapable of both 10Mbps and 100Mbps FDX/HDX settings
 u_height: 1
 is_full_depth: false
+front_image: true
+rear_image: true
 interfaces:
   - name: LAN 1
     type: 1000base-t