Allow configurable correlatorId generation in RpcClient

[janssk1]

The RpcClient class has a hardcoded algorithm for unique correlatorId generation. This works in most cases. However, i recently hit an issue where the 'correlatorId' was used (or misused) to encode some extra information needed by the receiver. It would be great if the RpcClient could be configured with a 'strategy' to generate unqiue correlatorIds.
Alternatively, the RpcClient should not touch the correlatorId if it is already provided in the arguments.

• RabbitMQ client version
  5.8.0

[michaelklishin]

This sounds like a great opportunity to contribute. This is open-source software after all ;)

[acogoluegnes]

This should be easy to add in a non-breaking way, especially now there's a RpcClient constructor with RpcClientParams. We've already done that in the Reactor extension, with a Supplier<String> to create the correlation ids.

A contribution would be indeed welcome.

[acogoluegnes]

Fixed in #638.