Passed to CommentNode by CommentThread for each top-level comment,
and by CommentNode for each reply. The callbacks are CommentThread's,
passed down unchanged.
depth: number
Sets the replies' --depth: the deeper, the narrower their indent.
dumpId: string
currentUser: SelfUser | null
onCommentCreated: (comment: Comment) => void
onCommentDeleted: (commentId: string) => void
onCommentUpdated: (comment: Comment) => void