Shortcut to mute notifications

[GentlemanHal]

Feature Request

What would you like to be able to do?
Quickly mute audio notifications from the Monitor page.

What problem would it solve?
This would allow people to easily mute audio notifications for a short time if they were in a meeting or something without needing to actually mess with settings.

I was thinking initially this could just be a keyboard shortcut. The space key might be a good choice as the m key is already used to navigate to the Monitor page.

[thesheps]

Do we think we'd want this to be on a configurable timeout, or just a spacebar toggle?

[GentlemanHal]

I was thinking just a spacebar toggle to keep it simple.

Possibly with an overlayed "mute" icon, although this could be added under a different improvement "issue" (I really hate they are called issues on GitHub 😢). Our icons are from icomoon, see https://github.com/build-canaries/nevergreen/wiki/contributing for more details about including new icons.