Implement links and HEAD for NetworkProtocol

Along the lines of changes we've made elsewhere, add Links, and a HEAD
handler for bmc NetworkProcotol instances.

Tested:
```
curl -vvvv --insecure  --user root:0penBmc https://192.168.7.2/redfish/v1/JsonSchemas/NetworkProtocol/NetworkProtocol.json


```

Returns a links header as part of the response.

Adding -X HEAD to the curl request results in the same header being
included.

Redfish service validator passes.

Redfish PROTOCOL VALIDATOR PASSES ! ! ! ! ! with zero failures.
Summary - PASS: 392, WARN: 0, FAIL: 0, NOT_TESTED: 32

Signed-off-by: Ed Tanous <edtanous@google.com>
Change-Id: Ib96f7c8d5d8d960000a1bb77065fc06d2829e4b8