Bug 1716518 - Upgrade bytes to v0.4.12 and v0.5.6. r=emilio

Cargo.lock

third_party/rust/bytes-0.4.12/.cargo-checksum.json

third_party/rust/bytes-0.4.12/CHANGELOG.md

third_party/rust/bytes-0.4.12/Cargo.toml

third_party/rust/bytes-0.4.12/LICENSE

third_party/rust/bytes-0.4.12/README.md

third_party/rust/bytes-0.4.12/benches/bytes.rs

third_party/rust/bytes-0.4.12/ci/before_deploy.ps1

third_party/rust/bytes-0.4.12/ci/before_deploy.sh

third_party/rust/bytes-0.4.12/ci/install.sh

third_party/rust/bytes-0.4.12/ci/script.sh

third_party/rust/bytes-0.4.12/ci/tsan

third_party/rust/bytes-0.4.12/src/buf/buf.rs

third_party/rust/bytes-0.4.12/src/buf/buf_mut.rs

third_party/rust/bytes-0.4.12/src/buf/chain.rs

third_party/rust/bytes-0.4.12/src/buf/from_buf.rs

third_party/rust/bytes-0.4.12/src/buf/into_buf.rs

third_party/rust/bytes-0.4.12/src/buf/iter.rs

third_party/rust/bytes-0.4.12/src/buf/mod.rs

third_party/rust/bytes-0.4.12/src/buf/reader.rs