[Feature]: A2aServer support multiple type of contentBlock.

[KomachiSion]

Is your feature request related to a problem? Please describe.
Current A2a Server only handle the Text type message input and just convert all type contentBlock to response message.

I think A2aServer should do some enhanments:

1. A2aServer should handle input with other contentBlock such as Video, Image.
2. A2aServer should filter some inner contentBlock like tool_result and tool_call not response to client by default.
3. What's more, A2aServer should allow user to config whether they want to get whole messages when task completed.

There are some TODOs in AgentScopeAgentExecutor.

• A2aServer should handle input with other contentBlock such as Video, Image. feat(a2a): For issue#234, A2a Server support input multiple type message. #304
• A2aServer should filter some inner contentBlock like tool_result and tool_call not response to client by default. feat(a2a): For issue#234, A2aServer support control message content by configuration. #364
• A2aServer should allow user to config whether they want to get whole messages when task completed. feat(a2a): For issue#234, A2aServer support control message content by configuration. #364

[KomachiSion]

please assign to me.