MM-22706: pass along set_online flag in websocket response (#14591)

* MM-22706: pass along set_online flag in websocket response

To let the client know whether a user has created a post without
being online or not, we get the set_online query param and
pass it down to the websocket event being passed down to the client.

With this PR, the "data" field of the `posted` event will contain
a `set_online` boolean field set to true/false depending on the
query_param set_online value set in the createPost call.

* Setting to false for auto responder

Co-authored-by: mattermod <mattermod@users.noreply.github.com>

app/team.go

@@ -1041,7 +1041,7 @@ func (a *App) postLeaveTeamMessage(user *model.User, channel *model.Channel) *mo
 		},
 	}
 
-	if _, err := a.CreatePost(post, channel, false); err != nil {
+	if _, err := a.CreatePost(post, channel, false, true); err != nil {
 		return model.NewAppError("postRemoveFromChannelMessage", "api.channel.post_user_add_remove_message_and_forget.error", nil, err.Error(), http.StatusInternalServerError)
 	}
 
@@ -1059,7 +1059,7 @@ func (a *App) postRemoveFromTeamMessage(user *model.User, channel *model.Channel
 		},
 	}
 
-	if _, err := a.CreatePost(post, channel, false); err != nil {
+	if _, err := a.CreatePost(post, channel, false, true); err != nil {
 		return model.NewAppError("postRemoveFromTeamMessage", "api.channel.post_user_add_remove_message_and_forget.error", nil, err.Error(), http.StatusInternalServerError)
 	}