separate car logger forwarded to cloudlog (#33170)

* car logger

* try this

* fix double printing!

* clean up

* need to import where we actually use it (card won't be in submodule)

* NullHandler does not forward everything properly, need propagate=False to stop root logger from printing

* card is staying

* set up

* forward
old-commit-hash: 12a7b7f7fb1d3a275314b0232795942a7ff3b955

common/swaglog.py

@@ -104,6 +104,15 @@ class UnixDomainSocketHandler(logging.Handler):
       pass
 
 
+class ForwardingHandler(logging.Handler):
+  def __init__(self, target_logger):
+    super().__init__()
+    self.target_logger = target_logger
+
+  def emit(self, record):
+    self.target_logger.handle(record)
+
+
 def add_file_handler(log):
   """
   Function to add the file log handler to swaglog.