Macro pipewire_wrapper::events_channel_builder

macro_rules! events_channel_builder {
    ($struct_name:ident, $($callback_field:ident => $callback:ident,)*) => { ... };
    ($channel_builder:ident, $events_builder:ident, $events_struct:ident, $events_type:ident, $($callback_field:ident => $callback:ident,)*) => { ... };
}

Implement build method for Events struct channel builder.