Macro wait_condition

macro_rules! wait_condition {
    ($ctx:expr, $key:expr, timeout: $timeout:expr, $predicate:expr $(,)?) => { ... };
    ($ctx:expr, $key:expr, $predicate:expr $(,)?) => { ... };
}

Create a durable condition wait whose predicate definition is fingerprinted from its inline Rust tokens.

The returned ConditionWaitCall must be awaited. The timeout form is wait_condition!(ctx, "approval", timeout: duration, || predicate).