Add Producer/Consumer Identifier

[Gsantomaggio]

The Identifier helps to correlate the entities with the logs and the UI.

Add the Identifier for producer and consumer. For the consumer is visible in the UI, like:

Code:

var producer = await Producer.Create(new ProducerConfig(system, stream)
{
   Identifier = $"my_producer_99",

logs:

 ProducerInfo(Stream=my_stream, Reference=, Identifier=my_producer_99)

Note: The producer doesn't have custom properties so won't be showed on the UI.

[codecov[bot]]

Codecov Report

Attention: 10 lines in your changes are missing coverage. Please review.

Comparison is base (fa8f66b) 92.12% compared to head (e26dbae) 92.12%.

:exclamation: Current head e26dbae differs from pull request most recent head b946c81. Consider uploading reports for the commit b946c81 to get more accurate results

Files	Patch %	Lines
RabbitMQ.Stream.Client/StreamSystem.cs	85.71%	0 Missing and 5 partials :warning:
RabbitMQ.Stream.Client/IProducer.cs	25.00%	3 Missing :warning:
RabbitMQ.Stream.Client/IConsumer.cs	50.00%	1 Missing :warning:
RabbitMQ.Stream.Client/RawSuperStreamConsumer.cs	75.00%	0 Missing and 1 partial :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #348 +/- ## ========================================== - Coverage 92.12% 92.12% -0.01% ========================================== Files 116 116 Lines 11320 11366 +46 Branches 897 899 +2 ========================================== + Hits 10429 10471 +42 - Misses 687 689 +2 - Partials 204 206 +2 ```

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