Add an Avro test data containing nested records

[sarutak]

This PR proposes to add an Avro format test data which contains nested records.
This data is necessary for testing the change proposed in this PR.

The schema of this test data is as follows.

{
    "name": "record1",
    "namespace": "ns1",
    "type": "record",
    "fields": [
        {
            "name": "f1",
            "type": {
                "name": "record2",
                "namespace": "ns2",
                "type": "record",
                "fields": [
                    {
                        "name": "f1_1",
                        "type": "string"
                    },  {
                        "name": "f1_2",
                        "type": "int"
                    },  {
                        "name": "f1_3",
                        "type": {
                            "name": "record3",
                            "namespace": "ns3",
                            "type": "record",
                            "fields": [
                                {
                                    "name": "f1_3_1",
                                    "type": "double"
                                }
                            ]
                        }
                    }
                ]
            }
        },  {
            "name": "f2",
            "type": "array",
            "items": {
                "name": "record4",
                "namespace": "ns4",
                "type": "record",
                "fields": [
                    {
                        "name": "f2_1",
                        "type": "boolean"
                    },  {
                        "name": "f2_2",
                        "type": "float"
                    }
                ]
            }
        }
    ]
}

And the JSON representation of the Avro format file is as follows.

{"f1":{"f1_1":"aaa","f1_2":10,"f1_3":{"f1_3_1":3.14}},"f2":[{"f2_1":true,"f2_2":1.2},{"f2_1":true,"f2_2":2.2}]}
{"f1":{"f1_1":"bbb","f1_2":20,"f1_3":{"f1_3_1":3.14}},"f2":[{"f2_1":false,"f2_2":10.2}]}

[alamb]

619 bytes looks good to me -- thank you very much @sarutak