Outbound serializer improvement

[jiangmengyu0409]

The current outbound serializer at https://github.com/Wiredcraft/nestjs-nsq-transporter/blob/master/src/requestor/outbound-event-serializer.ts#L9 will transfer the following format of message into an incorrect format:

Input message format:

{ meta: { transactionId: string; component: string; } data: { name: string; } }

Transferred format:

{ meta: { transactionId: string; component: string; timestamp: string; } data: { data: { name: string; } } }

This will cause nsq validator at consumer side to throw BadRequestException, as it was expecting the following format:
{ meta: { transactionId: string; component: string; timestamp: string; } data: { name: string; } }