feat: wrap on_message with typing (Chainlit#991)

Bot will show as typing while the run is running.

backend/chainlit/discord/app.py

@@ -240,7 +240,8 @@ async def process_discord_message(
  await on_chat_start()
 
  if on_message := config.code.on_message:
- await on_message(msg)
+ async with channel.typing():
+ await on_message(msg)
 
  if on_chat_end := config.code.on_chat_end:
  await on_chat_end()
@@ -269,7 +270,7 @@ async def on_ready():
 async def on_message(message: discord.Message):
  if not client.user or message.author == client.user:
  return
- 
+
  is_dm = isinstance(message.channel, discord.DMChannel)
  if not client.user.mentioned_in(message) and not is_dm:
  return