Add trivial implementations of FromClientHook

Sometimes it is nice to be able to return a `Box<dyn ClientHook>` or and
untyped `Client` from the functions that use FromClientHook like `bootstrap`.

This commit simply adds trivial implementations of `FromClientHook` for
`Box<dyn ClientHook>` and `Client`.

Author: griff

capnp/src/capability.rs

@@ -335,6 +335,21 @@ pub trait FromClientHook {
     }
 }
 
+#[cfg(feature = "alloc")]
+impl FromClientHook for alloc::boxed::Box<dyn ClientHook> {
+    fn new(hook: alloc::boxed::Box<dyn ClientHook>) -> Self {
+        hook
+    }
+
+    fn into_client_hook(self) -> alloc::boxed::Box<dyn ClientHook> {
+        self
+    }
+
+    fn as_client_hook(&self) -> &dyn ClientHook {
+        self.as_ref()
+    }
+}
+
 /// An untyped client.
 #[cfg(feature = "alloc")]
 pub struct Client {
@@ -383,6 +398,21 @@ impl Client {
     }
 }
 
+#[cfg(feature = "alloc")]
+impl FromClientHook for Client {
+    fn new(hook: alloc::boxed::Box<dyn ClientHook>) -> Self {
+        Client::new(hook)
+    }
+
+    fn into_client_hook(self) -> alloc::boxed::Box<dyn ClientHook> {
+        self.hook
+    }
+
+    fn as_client_hook(&self) -> &dyn ClientHook {
+        self.hook.as_ref()
+    }
+}
+
 /// The return value of Server::dispatch_call().
 #[cfg(feature = "alloc")]
 pub struct DispatchCallResult {