*: Fix clippy errors from upgrade to Rust 1.57 (#2365)

* core: Mark "unused" field with "_"

We need to keep this marker type to ensure that the type continues
to be required to be pinned.

* tranports/noise: Derive `Default` for `Config`

`false` is the default for `bool`, we can derive this.

* protocols/request-response: Remove unused fields

These are already included the `RequestResponseMessage::Request`
variant.

* *: Allow clippy's large-enum-variant lint

Tackling these suggestions would require performance measurement
which we don't want to do at this stage.

Co-authored-by: Max Inden <mail@max-inden.de>

core/src/transport/and_then.rs

@@ -77,7 +77,7 @@ where
         let future = AndThenFuture {
             inner: Either::Left(Box::pin(dialed_fut)),
             args: Some((self.fun, ConnectedPoint::Dialer { address: addr })),
-            marker: PhantomPinned,
+            _marker: PhantomPinned,
         };
         Ok(future)
     }
@@ -132,7 +132,7 @@ where
                             upgrade: AndThenFuture {
                                 inner: Either::Left(Box::pin(upgrade)),
                                 args: Some((this.fun.clone(), point)),
-                                marker: PhantomPinned,
+                                _marker: PhantomPinned,
                             },
                             local_addr,
                             remote_addr,
@@ -159,7 +159,7 @@ where
 pub struct AndThenFuture<TFut, TMap, TMapOut> {
     inner: Either<Pin<Box<TFut>>, Pin<Box<TMapOut>>>,
     args: Option<(TMap, ConnectedPoint)>,
-    marker: PhantomPinned,
+    _marker: PhantomPinned,
 }
 
 impl<TFut, TMap, TMapOut> Future for AndThenFuture<TFut, TMap, TMapOut>