[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/Cargo.toml

@@ -19,6 +19,7 @@ anyhow = { workspace = true }
 codex-arg0 = { workspace = true }
 codex-common = { workspace = true, features = ["cli"] }
 codex-core = { workspace = true }
+codex-file-search = { workspace = true }
 codex-login = { workspace = true }
 codex-protocol = { workspace = true }
 mcp-types = { workspace = true }