Create BatchItemFailure structs for DynamoDB, Kinesis, SQS (#410)

* Create streams.go

* go fmt

* Split StreamsEventResponse into duplicate structs

Co-authored-by: Bryan Moffatt <bmoffatt@users.noreply.github.com>
Co-authored-by: Carl Zogheib <carlzogh@amazon.com>

events/streams.go

@@ -0,0 +1,31 @@
+package events
+
+// KinesisEventResponse is the outer structure to report batch item failures for KinesisEvent.
+type KinesisEventResponse struct {
+	BatchItemFailures []KinesisBatchItemFailure `json:"batchItemFailures"`
+}
+
+// KinesisBatchItemFailure is the individual record which failed processing.
+type KinesisBatchItemFailure struct {
+	ItemIdentifier string `json:"itemIdentifier"`
+}
+
+// DynamoDBEventResponse is the outer structure to report batch item failures for DynamoDBEvent.
+type DynamoDBEventResponse struct {
+	BatchItemFailures []DynamoDBBatchItemFailure `json:"batchItemFailures"`
+}
+
+// DynamoDBBatchItemFailure is the individual record which failed processing.
+type DynamoDBBatchItemFailure struct {
+	ItemIdentifier string `json:"itemIdentifier"`
+}
+
+// SQSEventResponse is the outer structure to report batch item failures for SQSEvent.
+type SQSEventResponse struct {
+	BatchItemFailures []SQSBatchItemFailure `json:"batchItemFailures"`
+}
+
+// SQSBatchItemFailure is the individual record which failed processing.
+type SQSBatchItemFailure struct {
+	ItemIdentifier string `json:"itemIdentifier"`
+}