Currently checks are generated in a per-listener batch, and then we display them once all the checks are generated. When there are async checks involved, they hold up the display of all other generated checks. We by-convention generate async checks with a 6s timeout on server connections, but that's quite a long time in user-perception.

We should make it so that checks are displayed as soon as they are generated. Then other checks can be displayed as they stream in.

The main hold-up on doing this is rewriting some of the controller-dialog communication, because there's currently a gap where the dialog is opening and isn't yet listening to for the update events.

(Arguably this is related to T380378.)