Add feature to mute notifications

[dkozinn]

Figure an easy way to mute notifications such as when Reddit goes down.

Probably want to have it automatically revert or maybe send an indicator of how long to mute.

Want to be able to do this easily from a phone.

[dkozinn]

1. Create a script that checks for presence of a "mute" file before notifying
2. Modify *.service files to call that script instead of ntfy
3. Figure out how to create/delete mute file remotely (no ssh) - Webhook? Secured URL?