feat: Use prompt templates via Orchestration

[Jonas-Isr]

Context

AI/ai-sdk-java-backlog#184.

This PR enables users to consume pre-made prompt templates from the prompt registry of AI Core. Users can either reference a template via id, or via scenario, name, and version.

There is already a convenience layer to reference templates from #341 :

var template = TemplateConfig.reference().byId("21cb1358-0bf1-4f43-870b-00f14d0f9f16");
var configWithTemplate = config.withTemplateConfig(template);

var inputParams = Map.of("language", "Italian", "input", "cloud ERP systems");
var prompt = new OrchestrationPrompt(inputParams);

var result = client.chatCompletion(prompt, configWithTemplate);

Or, using scenario, name, and version to reference a template:

var template = TemplateConfig.reference().byScenario("test").name("test").version("0.0.1");

Feature scope:

• Enable consumption of prompt templates
• Add documentation (also for using convenience layer)

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

[CharlesDuboisSAP]

LGTM