Implement Cable schema

This commit implements Cable and Cable collection schema
on bmcweb.

Testing:
Validator:
@odata.id       /redfish/v1/Cables      odata   Exists  PASS
@odata.type     #CableCollection.CableCollection        odata   Exists
PASS
Members@odata.count     2       odata   Exists  PASS
Members Array (size: 2) links: Cable    Yes     ...
Members[0]      Link: /redfish/v1/Cables/dp0_cable0     link: Cable
Yes     PASS
Members[1]      Link: /redfish/v1/Cables/dp0_cable1     link: Cable
Yes     PASS
Description     Collection of Cable Entries     none    Yes     PASS
Name    Cable Collection        none    Yes     PASS
Oem     -       Resource.Oem    No      Optional

Property Name   Value   Type    Exists  Result
@odata.id       /redfish/v1/Cables/dp0_cable0   odata   Exists  PASS
@odata.type     #Cable.v1_0_0.Cable     odata   Exists  PASS
CableType               string  Yes     PASS
LengthMeters    -       number  No      Optional
Id      dp0_cable0      none    Yes     PASS
Name    Cable           none    Yes     PASS

Property Name   Value   Type    Exists  Result
@odata.id       /redfish/v1/Cables/dp0_cable1   odata   Exists  PASS
@odata.type     #Cable.v1_0_0.Cable     odata   Exists  PASS
CableType               string  Yes     PASS
LengthMeters    -       number  No      Optional
Id      dp0_cable1      none    Yes     PASS
Name    Cable           none    Yes     PASS

Note: Removed some of the fields that are optional to reduce commit msg

Tesing with Curl commands:
$ curl -k -X GET https://{$bmc}/redfish/v1/Cables
{
  "@odata.id": "/redfish/v1/Cables",
  "@odata.type": "#CableCollection.CableCollection",
  "Description": "Collection of Cable Entries",
  "Members": [
    {
      "@odata.id": "/redfish/v1/Cables/dp0_cable0"
    },
    {
      "@odata.id": "/redfish/v1/Cables/dp0_cable1"
    }
  ],
  "Members@odata.count": 2,
  "Name": "Cable Collection"
}

$ curl -k -X GET https://{$bmc}/redfish/v1/Cables/dp0_cable0
{
  "@odata.id": "/redfish/v1/Cables/dp0_cable0",
  "@odata.type": "#Cable.v1_0_0.Cable",
  "CableType": "",
  "Id": "dp0_cable0",
  "Name": "Cable"
}

$ curl -k -X GET https://{$bmc}/redfish/v1/Cables/dp0_cable1
{
  "@odata.id": "/redfish/v1/Cables/dp0_cable1",
  "@odata.type": "#Cable.v1_0_0.Cable",
  "CableType": "",
  "Id": "dp0_cable1",
  "Name": "Cable"
}

Set Length property to 1.5 meters using busctl, and check the properties
busctl set-property xyz.openbmc_project.Inventory.Manager \
 /xyz/openbmc_project/inventory/cables/dp0_cable0 \
 xyz.openbmc_project.Inventory.Item.Cable Length d 1.5

$ curl -k -X GET https://{$bmc}/redfish/v1/Cables/dp0_cable0
{
  "@odata.id": "/redfish/v1/Cables/dp0_cable0",
  "@odata.type": "#Cable.v1_0_0.Cable",
  "CableType": "",
  "Id": "dp0_cable0",
  "LengthMeters": 1.5,
  "Name": "Cable"
}

Signed-off-by: Shantappa Teekappanavar <sbteeks@yahoo.com>
Change-Id: I832ff1c1053f4d8100d04a42cc8046a61e8c1613
diff --git a/static/redfish/v1/$metadata/index.xml b/static/redfish/v1/$metadata/index.xml
index 60e3ede..f2d30ca 100644
--- a/static/redfish/v1/$metadata/index.xml
+++ b/static/redfish/v1/$metadata/index.xml
@@ -174,6 +174,14 @@
         <edmx:Include Namespace="Bios.v1_1_2"/>
         <edmx:Include Namespace="Bios.v1_2_0"/>
     </edmx:Reference>
+    <edmx:Reference Uri="/redfish/v1/schema/Cable_v1.xml">
+        <edmx:Include Namespace="Cable"/>
+        <edmx:Include Namespace="Cable.v1_0_0"/>
+        <edmx:Include Namespace="Cable.v1_1_0"/>
+    </edmx:Reference>
+    <edmx:Reference Uri="/redfish/v1/schema/CableCollection_v1.xml">
+        <edmx:Include Namespace="CableCollection"/>
+    </edmx:Reference>
     <edmx:Reference Uri="/redfish/v1/schema/Certificate_v1.xml">
         <edmx:Include Namespace="Certificate"/>
         <edmx:Include Namespace="Certificate.v1_0_0"/>