Modal Product Updates: App Rollbacks, Dynamic Batching, Sandbox Tunnels and OpenTelemetry

Modal shipped app rollbacks that let users revert a deployed app to a previous version from the dashboard or CLI, plus a @batched decorator that accumulates requests into dynamically sized batches to trade latency for throughput and GPU utilization. Sandbox objects can now forward TCP ports to the internet and exec additional processes, and logs can be exported to an OpenTelemetry provider. CPU cores and higher-end GPUs also got cheaper.