Add plugin outlet for group chats similar to `after-chat-channel-username`

Feature
1

Hey guys,

We noticed that on the latest Discourse, for individual chats, there is an after-chat-channel-username outlet, but such an equivalent doesn’t exist in the group chats after-chat-channel-username.

For example, we would like to render a :gear: icon or ... after the chat title to make it more intuitive that there are per-chat settings available.

In our community, most users didn’t even realize that clicking the chat title opens the settings panel.

2

If you’ve got someone who knows how, submitting a PR night make this happen sooner. In general they are open to adding plugin outlets as they don’t cost much.

3

From what I can see, the reason why that plugin doesn’t exist for groups is because the outlet has 1 argument given - the user messaging.

@pfaffman I suppose an {{else}} block and a plugin outlet with no outletArgs would work?