Macro relay_warn

Generated from cargo doc --no-deps -p nemo-relay -p nemo-relay-adaptive -p nemo-relay-pii-redaction -p nemo-relay-ffi -p nemo-relay-types -p nemo-relay-plugin -p nemo-relay-worker-proto -p nemo-relay-worker.

macro_rules! relay_warn {
    ($runtime:expr, target: $target:expr, fields: $fields:expr, $($arg:tt)+) => { ... };
    ($runtime:expr, target: $target:expr, $($arg:tt)+) => { ... };
}

Emit a formatted warn-level native-plugin record through the Relay host.