feat: search_tool migrate to bring you own tool of Responses API (#14274)

## Why

to support a new bring your own search tool in Responses
API(https://developers.openai.com/api/docs/guides/tools-tool-search#client-executed-tool-search)
we migrating our bm25 search tool to use official way to execute search
on client and communicate additional tools to the model.

## What
- replace the legacy `search_tool_bm25` flow with client-executed
`tool_search`
- add protocol, SSE, history, and normalization support for
`tool_search_call` and `tool_search_output`
- return namespaced Codex Apps search results and wire namespaced
follow-up tool calls back into MCP dispatch

codex-rs/app-server/tests/suite/v2/mcp_server_elicitation.rs

@@ -66,7 +66,7 @@ const DEFAULT_READ_TIMEOUT: std::time::Duration = std::time::Duration::from_secs
 const CONNECTOR_ID: &str = "calendar";
 const CONNECTOR_NAME: &str = "Calendar";
 const TOOL_NAME: &str = "calendar_confirm_action";
-const QUALIFIED_TOOL_NAME: &str = "mcp__codex_apps__calendar_confirm_action";
+const QUALIFIED_TOOL_NAME: &str = "mcp__codex_apps__calendar-confirm-action";
 const TOOL_CALL_ID: &str = "call-calendar-confirm";
 const ELICITATION_MESSAGE: &str = "Allow this request?";