[ergonomics]: Multiple tasks types with one worker

[geofmureithi]

Currently we have a one-worker one task requirement.
This issue will track the easing of this requirement.

Here is the suggested API:

WorkerBuilder::new("worker_name")
        .backend(storage)
        .build(|email: Email| async { "Hello, world!" })
        .build(|sms: Sms| async { "Hello, world!" })
        .run()
        .await
        .unwrap();

Related:

• Simpler hello world API #614

[geofmureithi]

After thinking about this a little more, This moves to the #wontfix basket.
Why? apalis already supports generics and enums, both which would solve this problem without any extra changes:

#[tokio::main]
async fn main() {
    let pool = PgPool::connect(&std::env::var("DATABASE_URL").unwrap())
        .await
        .unwrap();
    let mut store = SharedPostgresStorage::new(pool);

    let mut map_store = store.make_shared().unwrap();

    let mut int_store = store.make_shared().unwrap();

    map_store
        .push_stream(&mut stream::iter(vec![HashMap::<String, String>::new()]))
        .await
        .unwrap();
    int_store.push(99).await.unwrap();

    async fn send_reminder<T>(
        _: T,
        wrk: WorkerContext,
    ) -> Result<(), BoxDynError> {
        tokio::time::sleep(Duration::from_secs(2)).await;
        wrk.stop().unwrap();
        Ok(())
    }

    let int_worker = WorkerBuilder::new("rango-tango-2")
        .backend(int_store)
        .build(send_reminder);
    let map_worker = WorkerBuilder::new("rango-tango-1")
        .backend(map_store)
        .build(send_reminder);
    tokio::try_join!(int_worker.run(), map_worker.run()).unwrap();
}

Example extracted from:
https://github.com/apalis-dev/apalis-postgres/blob/main/examples/shared.rs