adk-java: integrate AGUI in addition to spring ai

** Please make sure you read the contribution guide and file the issues in the right place. **
[Contribution guide.](https://google.github.io/adk-docs/contributing-guide/)

**Is your feature request related to a problem? Please describe.**
It is helpful to integrate the AGUI protocol to have a rich UI. I did not find how to do such integration because adk-java uses its Runner and the agui spring-ai version uses its AguiService to run the agent. I need help to discuss how to do such integration. I am ready to contribute

**Describe the solution you'd like**
Enrich the spring ai integration with AGUI spring ai integration

**Describe alternatives you've considered**
I did not find any alternative

**Additional context**
Nothing to add for the moment