Makes channel_id and is_direct_message_channel consistent across desktop notifications, which also removes the need to lookup the channel from Chat Notification Manager.
Every time a desktop chat sound plays, there should be some visual cue as to why the sound was played in the first place.
This change follows the chat indicator preference:
- All New Messages - a blue dot is shown for all messages, so we attempt to play a sound every time
- Direct Messages, Mentions and Watched Threads - a green dot is shown for all urgent messages, so we attempt to play a sound for urgent chat notifications
- Only Mentions - only play chat sounds when user is mentioned
- Never - we never play chat sounds, as user wouldn’t know why the sound was played
