[mcp-server] Expose fuzzy file search in MCP (#2677)

## Summary
Expose a simple fuzzy file search implementation for mcp clients to work
with

## Testing
- [x] Tested locally

codex-rs/mcp-server/src/lib.rs

@@ -25,6 +25,7 @@ mod codex_tool_config;
 mod codex_tool_runner;
 mod error_code;
 mod exec_approval;
+mod fuzzy_file_search;
 mod json_to_toml;
 pub(crate) mod message_processor;
 mod outgoing_message;