state: Add Available mapping for Fabric Ports

- Utilize getResourceState and getResourceHealth utility function for
  resource's Status.State and Status.Health
- Map `Available` to Redfish `UnavailableOffline`

Tested:
- Unit tests passed
- Redfish Service Validator passed
- Request expected:
```
curl -k -v https://${bmc}/redfish/v1/Systems/system/FabricAdapters/disk_backplane0/Ports/dp0_connector1
```
Results in
```
{
  "@odata.id": "/redfish/v1/Systems/system/FabricAdapters/disk_backplane0/Ports/dp0_connector1",
  "@odata.type": "#Port.v1_11_0.Port",
  "Id": "dp0_connector1",
  ...
  "Status": {
    "Health": "OK",
    "State": "UnavailableOffline"
  }
}
```
if the resource is present but not available

Change-Id: I9220a9df2f602ed0712b10142782eeaa6f949ac9
Signed-off-by: Justin Nguyen <justinnanguyen@gmail.com>