[Feat]: Support for the data part, type form

### Is your feature request related to a problem? Please describe.

The inspector does not support data parts of the form type.
The inspector was able to capture the response JSON, but I can't interecat with it in the UI. So I cannot test agents with this feature using the inspector.

### Describe the solution you'd like

The inspector does not support data parts of the form type.
It would be nice to test agents with the data parts of the form type A2A feature.

Try using this agent that supports this feature:
https://github.com/a2aproject/a2a-samples/tree/main/samples/python/agents/adk_expense_reimbursement

The inspector was able to capture the response JSON, but I can't interecat with it in the UI. This my response to illustrate:

{
"contextId": "765fa301-94dc-4036-b1bb-2c673dbc19e3",
"final": true,
"kind": "status-update",
"status": {
"message": {
"contextId": "765fa301-94dc-4036-b1bb-2c673dbc19e3",
"kind": "message",
"messageId": "96e87427-8096-4bb2-a7e4-77a68f8b8ce4",
"parts": [
{
"data": {
"type": "form",
"form": {
"type": "object",
"properties": {
"date": {
"type": "string",
"format": "date",
"description": "Date of expense",
"title": "Date"
},
"amount": {
"type": "string",
"format": "number",
"description": "Amount of expense",
"title": "Amount"
},
"purpose": {
"type": "string",
"description": "Purpose of expense",
"title": "Purpose"
},
"request_id": {
"type": "string",
"description": "Request id",
"title": "Request ID"
}
},
"required": [
"purpose",
"request_id",
"date",
"amount"
]
},
"form_data": {
"purpose": "dinner with clients",
"request_id": "request_id_4836277",
"date": "December first",
"amount": "100 USD"
},
"instructions": null
},
"kind": "data"
}
],
"role": "agent",
"taskId": "2a1b39e5-0324-49a8-8e57-bab238e883eb"
},
"state": "input-required",
"timestamp": "2025-12-05T21:34:46.227881+00:00"
},
"taskId": "2a1b39e5-0324-49a8-8e57-bab238e883eb",
"id": "msg-1764970484298-q4zjs1xuq",
"validation_errors": []
}

### Describe alternatives you've considered

_No response_

### Additional context

_No response_

### Code of Conduct

- [x] I agree to follow this project's Code of Conduct

The issue is about adding UI support for the 'data' part with type 'form' in the inspector. Look at how other message parts (like text, tool-calls) are rendered in the UI, likely in a React component. The provided JSON shows the exact structure. Start by finding the component that renders message parts and extend it to handle 'kind': 'data' with 'type': 'form'. Check existing tests for message rendering to understand the pattern.

Scritto dal modello di indicizzazione a partire dal testo della issue.