Allow injecting the Codex Apps tools cache (#33113)

## What changed

- Accept a caller-provided `CodexAppsToolsCache` when constructing a `ThreadManager` and pass it through to the MCP manager.
- Add `ConnectorRuntimeManager::new_without_cache()` for an in-memory runtime that neither loads nor persists connector state on disk.
- Re-export `CodexAppsToolsCache` from `codex-core` and `codex-core-api` for embedders.

## Testing

- Verify that a cache-disabled connector runtime ignores existing disk state and publishes live tools without creating cache files.

GitOrigin-RevId: f52f4f27c425a8d84ad0d0987b30a6fc3c14d702

codex-rs/core/src/session/tests.rs

@@ -7734,6 +7734,7 @@ async fn plugin_availability_change_reuses_the_mcp_manager() {
     session.services.mcp_manager = Arc::new(McpManager::new_with_extensions(
         Arc::clone(&session.services.plugins_manager),
         registry,
+        crate::CodexAppsToolsCache::default(),
     ));
     let session = Arc::new(session);
     session