Add withClientId to ProducerSettings

[dragisak]

This is the same as akka/alpakka-kafka#1470

[pjfanning]

@mdedetrich seems ok to me - even for 1.0.0 - wdyt?

[dragisak]

This is adding parity with ConsumerSettings.withClientId

[mdedetrich]

According to CI this method already exists? https://github.com/apache/incubator-pekko-connectors-kafka/actions/runs/5548446654/jobs/10131476588?pr=108 ?

[error] /home/runner/work/incubator-pekko-connectors-kafka/incubator-pekko-connectors-kafka/core/src/main/scala/org/apache/pekko/kafka/ProducerSettings.scala:249:7: method withClientId is defined twice;
[error]   the conflicting method withClientId was defined at line 242:7
[error]   def withClientId(clientId: String): ProducerSettings[K, V] =

at https://github.com/apache/incubator-pekko-connectors-kafka/blob/1a7434f4af829b13ecdc4459850a3df41cc3fb43/core/src/main/scala/org/apache/pekko/kafka/ProducerSettings.scala#L242-L243

Actually according to git blame you already added this method (which we inherited from Akka)

[pjfanning]

I mistook the date of the alpakka merge - it was Feb 2022. I assumed it was 2023.

The code in incubator-pekko-connectors-kafka was forked in Sept 2023 so everything merged before Sept 2023 is in this pekko fork already.

[dragisak]

Ha. I created this PR because my Akka code change didn't make into the release. Closing this then