Include support for Kafka Record properties

[aaron-613]

When publishing/sending a Record, the producer has the option of including an optional set of key/value pair Properties. These are passed along with the message as metadata outside the payload/value.

Sample code:

List<Header> headers = Arrays.asList(new RecordHeader("header_key", "header_value".getBytes()));
ProducerRecord<String, DataRecord> record2 = new ProducerRecord<>("topic", 0, key, value, headers);

These values are not represented in the resulting Solace message. Perhaps they could be included in the User Properties map?

Or more exciting: allowing them to be used in constructing a more descriptive Solace topic.