3cb0030fe9
delegation: Implement list delegation
```rust
reuse prefix::{a, b, c};
```
Using design described in https://github.com/rust-lang/rfcs/pull/3530#issuecomment-2020869823 (the lists are desugared at macro expansion time).
List delegations are expanded eagerly when encountered, similarly to `#[cfg]`s, and not enqueued for later resolution/expansion like regular macros or glob delegation (https://github.com/rust-lang/rust/pull/124135).
Part of https://github.com/rust-lang/rust/issues/118212.