StructuredInputs samples, tests, README updates

[jpalvarezl]

This pull request introduces support for structured inputs in the Azure AI Agents Java SDK, enabling users to define named parameters for agents and substitute their values at runtime. This makes agent definitions more flexible and reusable across different contexts. The changes include updates to the SDK's API, documentation, samples, and tests to demonstrate and verify the new feature.

Structured Input Support

• Added new methods to ResponsesClient and ResponsesAsyncClient for creating responses (both regular and streaming) using structured input values that are substituted into the agent's prompt template at runtime. These methods accept a map of input names to values and handle serialization and request construction. [1] [2] [3] [4]
• Updated the sample CreateResponseWithStructuredInput.java to demonstrate defining structured inputs on an agent and using the new API methods to create responses with those inputs.
• Added a new section to the README.md explaining how to use structured inputs, including code examples and references to the sample file.

Testing and Validation

• Added comprehensive unit tests in both sync (AgentsTests.java) and async (AgentsAsyncTests.java) test suites to verify agent creation with structured inputs and response generation using the new API methods. [1] [2] [3] [4] [5]

Other

• Updated the assets tag in assets.json to reflect the new version.