refactor!: replace Endpoint addr/id getters

Rather than `Endpoint` having getters for `addr`
(`get_socket_addr_by_id`) and `id` (`get_connection_id`) there are now
only getters for `Connection`, either by `addr`
(`get_connection_by_addr`) or by `id` (`get_connection_by_id`).

For now this mostly adds indirection for callers, who can call
`Connection::id` or `Connection::remote_address` on the result to
achieve the same outcome as before.

BREAKING CHANGE: `Endpoint::get_connection_id` and
`Endpoint::get_socket_addr_by_id` have been removed.
`Endpoint::get_connection_by_addr` and `Endpoint::get_connection_by_id`
can be used instead to get a `Connection`, from which the `id` or
`remote_address` can be retrieved.

src/connection_pool.rs

@@ -148,12 +148,11 @@ struct Store<I: ConnId> {
     id_gen: IdGen,
 }
 
-/// Unique key identifying a connection. Two connections will always have distict keys even if they
-/// have the same socket address.
+/// An application-defined identifier for a connection.
 pub trait ConnId:
     Clone + Copy + Eq + PartialEq + Ord + PartialOrd + Default + Send + Sync + 'static
 {
-    /// Generate
+    /// Generate an ID for the given `SocketAddr`.
     fn generate(socket_addr: &SocketAddr) -> Self;
 }
 

src/connections.rs

@@ -54,6 +54,11 @@ impl<I: ConnId> Connection<I> {
         Self { quic_conn, remover }
     }
 
+    /// Get the ID under which the connection is stored in the pool.
+    pub fn id(&self) -> I {
+        self.remover.id()
+    }
+
     /// Get the address of the connected peer.
     pub fn remote_address(&self) -> SocketAddr {
         self.quic_conn.remote_address()

src/endpoint.rs

@@ -360,20 +360,20 @@ impl<I: ConnId> Endpoint<I> {
         }
     }
 
-    /// Get the connection ID of an existing pooled connection with the provided socket address.
-    pub async fn get_connection_id(&self, addr: &SocketAddr) -> Option<I> {
+    /// Get the existing `Connection` for a `SocketAddr`.
+    pub async fn get_connection_by_addr(&self, addr: &SocketAddr) -> Option<Connection<I>> {
         self.connection_pool
             .get_by_addr(addr)
             .await
-            .map(|(_, remover)| remover.id())
+            .map(|(connection, remover)| Connection::new(connection, remover))
     }
 
-    /// Get the `SocketAddr` of an existing pooled connection with the provided connection ID.
-    pub async fn get_socket_addr_by_id(&self, id: &I) -> Option<SocketAddr> {
+    /// Get the existing `Connection` for the given ID.
+    pub async fn get_connection_by_id(&self, id: &I) -> Option<Connection<I>> {
         self.connection_pool
             .get_by_id(id)
             .await
-            .map(|(_, remover)| *remover.remote_addr())
+            .map(|(connection, remover)| Connection::new(connection, remover))
     }
 
     /// Open a bi-directional stream with a given peer.