chore(proxy): disallow unwrap and unimplemented (#10142)

As the title says, I updated the lint rules to no longer allow unwrap or
unimplemented.

Three special cases:
* Tests are allowed to use them
* std::sync::Mutex lock().unwrap() is common because it's usually
correct to continue panicking on poison
* `tokio::spawn_blocking(...).await.unwrap()` is common because it will
only error if the blocking fn panics, so continuing the panic is also
correct

I've introduced two extension traits to help with these last two, that
are a bit more explicit so they don't need an expect message every time.

proxy/src/protocol2.rs

@@ -396,6 +396,7 @@ impl NetworkEndianIpv6 {
 }
 
 #[cfg(test)]
+#[expect(clippy::unwrap_used)]
 mod tests {
     use tokio::io::AsyncReadExt;