Support for reading CloudWatch Logs JSON using json codec

[dlvenable]

Is your feature request related to a problem? Please describe.

We want to be able to decode CloudWatch Logs subscription filters.

https://docs.aws.amazon.com/AmazonCloudWatch/latest/logs/SubscriptionFilters.html

{
    "owner": "111111111111",
    "logGroup": "CloudTrail/logs",
    "logStream": "111111111111_CloudTrail/logs_us-east-1",
    "subscriptionFilters": [
        "Destination"
    ],
    "messageType": "DATA_MESSAGE",
    "logEvents": [
        {
            "id": "31953106606966983378809025079804211143289615424298221568",
            "timestamp": 1432826855000,
            "message": "{\"eventVersion\":\"1.03\",\"userIdentity\":{\"type\":\"Root\"}"
        },
        {
            "id": "31953106606966983378809025079804211143289615424298221569",
            "timestamp": 1432826855000,
            "message": "{\"eventVersion\":\"1.03\",\"userIdentity\":{\"type\":\"Root\"}"
        },
        {
            "id": "31953106606966983378809025079804211143289615424298221570",
            "timestamp": 1432826855000,
            "message": "{\"eventVersion\":\"1.03\",\"userIdentity\":{\"type\":\"Root\"}"
        }
    ]
}

There are a few things the existing json codec will have trouble with here.

1. It picks the first JSON array. In this case it will be subscriptionFilters rather than logEvents.
2. There is useful metadata that never appears in the generated events. For example, logStream.

Describe the solution you'd like

I'd like the existing json codec to support a few new features.

1. Allow the pipeline author to choose the key within the JSON to parse.

codec:
  json:
    key_name: logEvents

The key_name matches the json output codec's similar configuration.

data-prepper/data-prepper-plugins/parse-json-processor/src/main/java/org/opensearch/dataprepper/plugins/codec/json/JsonOutputCodecConfig.java

Lines 13 to 15 in 76d76fc

	@JsonProperty("key_name")
	@Size(min = 1, max = 2048)
	private String keyName = DEFAULT_KEY_NAME;

2. Allow selecting data from the root of the JSON to include in each object.

codec:
  json:
    include_keys: ['owner', logGroup', 'logStream' ]

This would output events like the following:

{
  "id": "31953106606966983378809025079804211143289615424298221568",
  "timestamp": 1432826855000,
  "message": "{\"eventVersion\":\"1.03\",\"userIdentity\":{\"type\":\"Root\"}",
  "owner": "111111111111",
  "logGroup": "CloudTrail/logs",
  "logStream": "111111111111_CloudTrail/logs_us-east-1",
}

3. Allow selecting data from the root of the JSON to include in the metadata for each object.

codec:
  json:
    include_keys_metadata: ['owner', logGroup', 'logStream' ]

[sb2k16]

I would like to work on this issue. Could you please assign this to me.