notifyMentions(mentionerUserId: string,body: string,contextType: "comment" | "dump" | "playlist" | "chat",contextId: string,contextTitle: string,dumpId?: string,skipUserId?: (userId: string) => boolean): void
Notifies every user @mentioned in body, except its author, that they were
mentioned in the comment, dump, playlist or chat message contextId. Call
it again after each edit: a user already notified for this context isn't
notified twice. skipUserId spares a mentioned user; the chat uses it for
those who have it open.