Add GrpcStreamBroadcaster.is_running method

Based on how it is configured, the `GrpcStreamBroadcaster` can stop
running when the retry limit has been reached or when the server
closes the connection.

The `is_running` method can be used to find out if that has happened.

Signed-off-by: Sahas Subramanian <[email protected]>

Author: shsms

src/frequenz/client/base/streaming.py

@@ -71,6 +71,15 @@ def new_receiver(self, maxsize: int = 50) -> channels.Receiver[OutputT]:
         """
         return self._channel.new_receiver(limit=maxsize)
 
+    @property
+    def is_running(self) -> bool:
+        """Return whether the streaming helper is running.
+
+        Returns:
+            Whether the streaming helper is running.
+        """
+        return not self._task.done()
+
     async def stop(self) -> None:
         """Stop the streaming helper."""
         if self._task.done():