Improvements to recording countdown

[kmcnaught]

Reviving discussions on earlier draft PR...

The main purpose of the countdown dialog is to
(a) to provide feedback on recording state (the 3 seconds and the 10 second recording time) and
(b) provide an option to Cancel at any point in the 13 seconds, either by pressing a Cancel button, or pressing Esc.

NVDA gets in the way by reading out all of the dialog, so you miss the countdown. Based on earlier discussions it sounds like the UX is pretty good with VoiceOver on Mac, but I wasn't sure if these changes were merged or not?

It would be good to resume these discussions and get some feedback.