tokio-stream: implement FusedStream for Fuse (#8090)

tokio-stream/src/stream_ext/fuse.rs

@@ -1,5 +1,6 @@
 use crate::Stream;
 
+use futures_core::FusedStream;
 use pin_project_lite::pin_project;
 use std::pin::Pin;
 use std::task::{ready, Context, Poll};
@@ -51,3 +52,12 @@ where
         }
     }
 }
+
+impl<T> FusedStream for Fuse<T>
+where
+    T: Stream,
+{
+    fn is_terminated(&self) -> bool {
+        self.stream.is_none()
+    }
+}