fix(relay): wake the relay Listener on close

[stormshield-frb]

Description

When closing a relayed Listener manually, the TransportEvent::ListenerClosed generated by the relay::priv_client::Transport is never forwarded back up to the Swarm, causing the Swarm to never remove the corresponding listener and never emitting the SwarmEvent::ListenerClosed event.

This happens because, when stopping a relayed listener manually, the call to the close() function, is done outside the poll function, which mean nothing is triggering a wake up call to wake up the polling.

Unfortunately, even if the listeners (SelectAll) is always polled after a call to the close method, since SelectAll uses a FuturesUnordered internally, the poll does nothing. Indeed, the FuturesUnordered states that:

/// This structure is optimized to manage a large number of futures.
/// Futures managed by [`FuturesUnordered`] will only be polled when they
/// generate wake-up notifications. This reduces the required amount of work
/// needed to poll large numbers of futures.

Since means that when closing a relayed listener manually (calling swarm.remove_listener), it is never removed.

This PR fixes that by triggering a waker when calling the close function.

Notes & open questions

Change checklist

• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• A changelog entry has been made in the appropriate crates

[jxs]

LGTM, thanks François!