Add metadata files for tokio-stream. am: 27b7b7879e am: 26d97a0a81 am: b76f6fedb0

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/tokio-stream/+/1558922

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: Iaf318a43f14823098d8b905c9e9aeb73366ee99a