refactor(iroh-willow): refactor peer manager so that proptest passes reliably (#2727)

## Description

Fixes #2695 

* Refactor peer manager to really keep track of all connections, the
previous logic of a single peer state was flawed for simultaneous
accepts while closing previous connections.
* Better debuggability of reconciler
* Add proptest from #2695 and refactor to run in both directions
simultaneously.

## Breaking Changes

<!-- Optional, if there are any breaking changes document them,
including how to migrate older code. -->

## Notes & open questions

<!-- Any notes, remarks or open questions you have to make about the PR.
-->

## Change checklist

- [ ] Self-review.
- [ ] Documentation updates following the [style
guide](https://rust-lang.github.io/rfcs/1574-more-api-documentation-conventions.html#appendix-a-full-conventions-text),
if relevant.
- [ ] Tests if relevant.
- [ ] All breaking changes documented.

---------

Co-authored-by: Philipp Krüger <philipp.krueger1@gmail.com>

Author: Frando

Cargo.lock

@@ -265,9 +265,8 @@ impl Drop for ActorHandle {
 
             // shutdown
             let shutdown = move || {
-                if let Err(err) = inbox_tx.blocking_send(Input::Shutdown { reply: None }) {
-                    warn!(?err, "Failed to send shutdown");
-                } else if let Err(err) = handle.join() {
+                inbox_tx.blocking_send(Input::Shutdown { reply: None }).ok();
+                if let Err(err) = handle.join() {
                     warn!(?err, "Failed to join sync actor");
                 }
             };