Extend schema to support reporting of FDB table (wired clients)

Extend state/unit.yml to report triplet that states which mac
  has been learned on which port in which vlan.
Example of "mac-forwarding-table" in json format:
...
            "mac-forwarding-table": {
                "overflow": false,
                "Ethernet0":    {
                    "1":    ["90:3c:b3:6a:e3:59"]
                },
                "Ethernet1":    {
                    "1":    ["90:3c:b3:6a:e4:d5"]
                },
                "Ethernet47":   {
                    "1":    ["ac:1f:6b:65:a4:86"]
                },
                "Ethernet46":   {
                    "1":    ["ac:1f:6b:65:a4:89"]
                }
            },
...

Signed-off-by: Oleksandr Mazur <oleksandr.mazur@plvision.eu>

state/mac-address-list.yml

@@ -0,0 +1,22 @@
+type: object
+description:
+  This section describes the global (device-wise) mac-address-list (FDB table / wired clients).
+properties:
+  overflow:
+    description:
+      Flag indicates that device could report an amount of FDB entries, which is bigger than what cloud had requested.
+    type: boolean
+additionalProperties:
+  type: object
+  additionalProperties:
+    description:
+      VID (vlan id) identifier
+    type: array
+    items:
+      type: string
+examples:
+  - overflow: true
+    Ethernet1:
+      '1': [ 'AABBCCDDEEFF', '112233445566']
+    Ethernet2:
+      '10': [ '11BBCCDDEEFF', '332233445566']

state/state.yml

@@ -52,3 +52,5 @@ properties:
         patternProperties:
           "^(eth|lan|wan)[0-9]*$":
             $ref: "https://ucentral.io/state/v1/link-state/"
+  mac-address-list:
+    $ref: "https://ucentral.io/state/v1/mac-address-list/"