Add bug component for Rust (688011) to OWNERS of tokio* am: b70cc2907a am: 3575c34ee9 am: df306a0fef am: b5cfb3456d

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/tokio-stream/+/2689067

Change-Id: I041ecdbccfd333e0eb3c24db0f7ef89bcfb8e7c4
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>