Add muting for specific SMS recipients

It would be great if you added a way to mute specific people from the SMS screen. If I mute someone on my phone, my phone won't notify me but my join extension in Chrome still detects a new message and displays it. If we could mute directly from the join app, we would still receive the messages from the muted person (which is fine, it's a mute, not a block), but they wouldn't disturb us.