Add support for zmpop

[gkorland]

No description provided.

[jaymell]

Hi -- thanks for the PR! Fixing clippy warnings is fine, but can we put them in a separate PR for organization's sake?

EDIT: I have since seen other PR for clippy -- apologies for my limited PR buffer size 😹

[djc]

The OP already has the clippy warnings fixed in #604, so we should get that landed first. :)

[gkorland]

@djc @jaymell I'm sorry for the broken PR, I guess this is what happens when you don't write tests.
I did review the the tests and I don't see any tests for the APIs.

e.g. looking at the test for SET operations it seems like the test doesn't really test the API, but only test the raw cmd API.

fn test_set_ops() {
    let ctx = TestContext::new();
    let mut con = ctx.connection();

    redis::cmd("SADD").arg("foo").arg(1).execute(&mut con);
    redis::cmd("SADD").arg("foo").arg(2).execute(&mut con);
    redis::cmd("SADD").arg("foo").arg(3).execute(&mut con);

    let mut s: Vec<i32> = redis::cmd("SMEMBERS").arg("foo").query(&mut con).unwrap();
    s.sort_unstable();
    assert_eq!(s.len(), 3);
    assert_eq!(&s, &[1, 2, 3]);

    let set: HashSet<i32> = redis::cmd("SMEMBERS").arg("foo").query(&mut con).unwrap();
    assert_eq!(set.len(), 3);
    assert!(set.contains(&1i32));
    assert!(set.contains(&2i32));
    assert!(set.contains(&3i32));

    let set: BTreeSet<i32> = redis::cmd("SMEMBERS").arg("foo").query(&mut con).unwrap();
    assert_eq!(set.len(), 3);
    assert!(set.contains(&1i32));
    assert!(set.contains(&2i32));
    assert!(set.contains(&3i32));
}

[djc]

Would you mind rebasing this on main so the clippy fixes go away?