[FEATURE] Support S3 event notifications

[eugene100]

Problem:
I'm going to implement the next scenario. When a new file uploaded to S3 bucket it should be checked by AV. S3 event notifications can send messages to a SQS notification queue, but format of a message is different than mousetrap expected.

Suggested solution::
Add extra validation for message what expected S3 message pattern: "eventSource": "aws:s3"

Example of S3 message:

{
    "Records": [
        {
            "eventVersion": "2.1",
            "eventSource": "aws:s3",
            "awsRegion": "us-east-1",
            "eventTime": "2020-11-15T17:03:43.718Z",
            "eventName": "ObjectCreated:Put",
            "userIdentity": {
                "principalId": "AWS:xxx"
            },
            "requestParameters": {
                "sourceIPAddress": "4.79.40.174"
            },
            "responseElements": {
                "x-amz-request-id": "7F3CBD63501C6716",
                "x-amz-id-2": "IETQzK13GB6UwPKyHVA20DqxsSHOVy9O5jtPronMbykSLJzErxPghyzGbKmeQnZ7vfBHXoe1Y2JFcSfjlI5hmq1z6S3JBO2M"
            },
            "s3": {
                "s3SchemaVersion": "1.0",
                "configurationId": "eugene-av",
                "bucket": {
                    "name": "eugene-av",
                    "ownerIdentity": {
                        "principalId": "A277FPSBMIAL09"
                    },
                    "arn": "arn:aws:s3:::eugene-av"
                },
                "object": {
                    "key": "photo_2020-10-29_19-20-49.jpg",
                    "size": 30573,
                    "eTag": "f9ee8886f30bd40963d327ef2d81a1f3",
                    "sequencer": "005FB15F7536F961A3"
                }
            }
        }
    ]
}

[amitlt]

Sounds like an excellent addition 👍