interactive notification group configuration

[shazow]

we want to be able to preconfigure how to treat various groups, but more user-friendly would be to have android-style buttons that let you:

1. "Snooze" notifications from any group for some time interval (15min, 30min, 1hr, 2hr, 8hr) -- perhaps the default intervals should be configurable
2. "Turn Off" notifications from any group, let's say an app is really spammy and we don't want the notifications, we should be able to turn it off.

I imagine this is getting written as a settings "overlay" in XDG_STATE_HOME somewhere, which we could "copy" into our normal declarative config later if we want (for better nix management experience).