Add NFTokenPage objects in account_objects response.

[mounikakun]

Request:

{
    "method": "account_objects",
    "params": [
        {
            "account": "rUaxN8qVfAt3StHm363JwjhuzucmDws5KH",
            "limit": 400,
            "ledger_index":"validated"
        }
    ]
}

Clio response:

{
    "result": {
        "ledger_hash": "17C8E75260D0E3084348414FE64B3067C49C5AEB12AE7E50925D2B576C306D19",
        "ledger_index": 29485971,
        "validated": true,
        "limit": 400,
        "account": "rUaxN8qVfAt3StHm363JwjhuzucmDws5KH",
        "account_objects": [],
        "status": "success"
    },
    "warnings": [
        {
            "id": 2001,
            "message": "This is a clio server. clio only serves validated data. If you want to talk to rippled, include 'ledger_index':'current' in your request"
        }
    ]
}

Rippled response:

{
    "result": {
        "account": "rUaxN8qVfAt3StHm363JwjhuzucmDws5KH",
        "account_objects": [
            {
                "Flags": 0,
                "LedgerEntryType": "NFTokenPage",
                "NFTokens": [
                    {
                        "NFToken": {
                            "NFTokenID": "0000000079C992D7020E038D8B6B902801078B0BA7A74C420000099B00000000"
                        }
                    }
                ],
                "PreviousTxnID": "4B696547299B9513BA22A4C5DD5DC286710E9AAE0C6F639EFC46CA51BF7E0427",
                "PreviousTxnLgrSeq": 29485687,
                "index": "79C992D7020E038D8B6B902801078B0BA7A74C42FFFFFFFFFFFFFFFFFFFFFFFF"
            }
        ],
        "ledger_hash": "0CD1C50154F6BCDCAA2CAF0FD9D0A09D10FFB403A4F3FC428D252E4B23868A82",
        "ledger_index": 29485988,
        "status": "success",
        "validated": true
    }
}

[cindyyan317]

Looks like we need to sync with this PR XRPLF/rippled#4352