feat: [Orchestration] Support for Orchestration config persistence

[Jonas-Isr]

Context

• https://github.com/orgs/SAP/projects/62/views/7?pane=issue&itemId=138596334&issue=SAP%7Cai-sdk-java-backlog%7C343

The PR enables the management of Orchestration Configs in prompt registry (create, delete, list via generated code and new client) as well as convenience to use these Orchestration Configs in the OrchestrationClient.

Sample of new convenience:

// create OrchestrationPrompt (for placeholder values and history) with already existing convenience
List<Message> history = List.of(new SystemMessage("System Message"));
OrchestrationPrompt prompt = new OrchestrationPrompt(Map.of("placeholder", "value")).messageHistory(history);

// create (newly added) OrchestrationConfigReference to refer to saved Orchestration config
OrchestrationConfigReference reference =
    OrchestrationConfigReference.fromScenario("scenario").name("name").version("0.0.1");

// use OrchestrationClient todo chat completion with the referenced config
OrchestrationChatResponse response = client.executeRequestFromReference(prompt, reference);

Feature scope:

• add new OchestrationConfigClient in prompt registry
  • unit and e2e tests for generated code and new client in prompt registry
• convenience for use with OrchestrationClient
  • unit and e2e tests for new convenience

Definition of Done

• Functionality scope stated & covered
• Tests cover the scope above
• Error handling created / updated & covered by the tests above
• Aligned changes with the JavaScript SDK
• Documentation updated
• Release notes updated

[Jonas-Isr]

I decided against making this a sealed interface plus two permitted classes because I felt that would be a bit of an overkill for such little logic. Would be interested in your thoughts about that.

[newtork]

(Major/Discussion)

I don't think we want to extend a custom class from generated code. Did we do that before? Is there no other way to apply mixins? Otherwise this has a code smell; we're introducing hand-written public API code for the sake of a workaround.

[CharlesDuboisSAP]

We did that in PromptClient and GroundingClient. It's only to add mix-ins.

[newtork]

(Minor)

You could've turned this into a currying builder, when the classes were interfaces.

return (name) -> (version) -> new OrchestrationConfigReference(null, scenario, name, version);

[CharlesDuboisSAP]

Looking good 😎