PubSub JSON DataSetWriterId should be a UInt16, not a String

[mregen]

Describe the bug In this Mantis Issue: (errata 1.04.2)

4327	DataSetWriterId field in JSON DataSetMessage	Changed DataType of the DataSetWriterId in a JSON DataSetMessage from String to UInt16 to be consistent with other definitions.

the datatype was changed from string to UInt16.

To Reproduce Send PubSub JSON encoded message to cloud, value is set to string like: "DataSetWriterId": "uat46f9f8f82fd5c1b42a7de31b5dc2c11ef418a62f",

Expected behavior DatasetWriterId is a UInt16

Additional context see also https://github.com/Azure/Industrial-IoT/blob/master/docs/dev-guides/telemetry-messages-format.md