Update to Cisco C8500-12X [✅ passed] (#2928)

* Added images and weight info to C8500-12X

* Tweaked rear image colors a bit to be more in line with front

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Co-authored-by: Florian Knorn <fknorn@cisco.com>

device-types/Cisco/C8500-12X.yaml

@@ -5,6 +5,11 @@ slug: cisco-c8500-12x
 part_number: C8500-12X
 u_height: 1
 is_full_depth: true
+weight: 20.25
+weight_unit: lb
+front_image: true
+rear_image: true
+comments: '[Cisco Catalyst 8500 Series Edge Platforms Data Sheet](https://www.cisco.com/c/en/us/products/collateral/routers/catalyst-8500-series-edge-platforms/datasheet-c78-744089.html)'
 console-ports:
   - name: con 0
     type: rj-45