Include receiver name in its string representation (#439)

The string representation of a receiver is used in logging, and
without this, it is impossible to identify which receiver is meant,
from looking at the logs.

Author: shsms

RELEASE_NOTES.md

@@ -15,3 +15,5 @@
 ## Bug Fixes
 
 - Fix `NopReceiver.ready()` to properly terminate when receiver is closed.
+
+- The `__str__` representation of broadcast receivers now include the receiver's name.

src/frequenz/channels/_broadcast.py

@@ -515,7 +515,7 @@ def close(self) -> None:
 
     def __str__(self) -> str:
         """Return a string representation of this receiver."""
-        return f"{self._channel}:{type(self).__name__}"
+        return f"{self._channel}:{type(self).__name__}:{self._name}"
 
     def __repr__(self) -> str:
         """Return a string representation of this receiver."""