bots: Modify 'extract_query_without_mention' to take bot name as input.

This is done so that Embedded bot system can also make use of
this function directly, as only client name is needed in this function,
and the type of client need not be ExternalBotHandler.

Also, there would be ambiguity as what type of BotHandler is
passed in the arguments: EmbeddedBotHandler or ExternalBotHandler.

Author: abhijeetkaur

zulip_bots/zulip_bots/lib.py

@@ -162,13 +162,23 @@ def state(self, default):
         yield new_state
         self.set_state(new_state)
 
-def extract_query_without_mention(message, client):
-    # type: (Dict[str, Any], ExternalBotHandler) -> str
+def extract_query_without_mention(message, at_mention_bot_name):
+    # type: (Dict[str, Any], str) -> str
     """
     If the bot is the first @mention in the message, then this function returns
     the message with the bot's @mention removed.  Otherwise, it returns None.
+    This function is being leveraged by two systems; external bot system and embedded bot system.
+    This function is being called by:
+    1. 'run_message_handler_for_bot' function (zulip_bots/lib.py file in zulip/python-zulip-api
+        repository) that executes/runs/calls external bots.
+    2. 'consume' function in EmbeddedBotWorker class (zerver/worker/queue_processors.py
+        file in zulip/zulip repository) that executes/runs/calls embedded bots.
+
+    Since, this is a general utility function for any working bot, it is planned to be an independent
+    function for now. Any refactoring should correctly be reflected in all the bot systems using this
+    function.
     """
-    bot_mention = r'^@(\*\*{0}\*\*)'.format(client.full_name)
+    bot_mention = r'^@(\*\*{0}\*\*)'.format(at_mention_bot_name)
     start_with_mention = re.compile(bot_mention).match(message['content'])
     if start_with_mention is None:
         return None