Feature request: add count-down screen

[Hugo-Heagren]

(Frustratingly) some websites do not play nicely with passwordstore's OTP browser plugin, and require me to type in the TOTP by hand. Android 2FA vaults like Aegis have a facility for displaying the code with a countdown of how long it is until the code stops being valid. It would be good to add this to the emacs package, so that I can display the code in a nicely-formatted buffer, with a countdown, in one window, while I type it out in the browswer in the other.