Support stdio transport server on the session/new request in the acp mode.

### Describe the bug

Agent Client Protocol says [All agents MUST support this transport](https://agentclientprotocol.com/protocol/v1/schema#mcpserver) but Copilot CLI has Rejected these stdio servers.

### Affected version

GitHub Copilot CLI 1.0.63

### Steps to reproduce the behavior

1. Create ACP Client and it connect to Copilot CLI
2. request a `session/new` request with `mcpServers` config include the stdio transport servers.
3. Copilot CLI will rejected these stdio servers. (I discovered Copilot CLI says reject in the process log)

### Expected behavior

These will launch correctly stdio transport MCP Servers via `session/new` request

### Additional context

Currently workaround:
mcpServers config pass to copilot cli via `--additional-mcp-config=JSON` args, these works fine.

Is that the behavior correct?

thanks.

從處理 session/new 請求的 ACP 模式處理常式開始，追蹤其 mcpServers 設定的處理方式，並將其與已經正常運作的 --additional-mcp-config 路徑進行比較。使用 stdio 傳輸伺服器重現該請求，並驗證伺服器能夠透過 session/new 成功啟動而不會遭到拒絕。

由索引模型根據 Issue 內容生成。