Add PWA, service worker and Web Push

- Use new notification request/opt-in flow for push
- Implement unsubscribing
- Implement muting
- Implement emojis in title
- Add iOS specific PWA warning
- Don’t use websockets when web push is enabled
- Fix duplicate notifications
- Implement default web push setting
- Implement changing subscription type
- Implement web push subscription refresh
- Implement web push notification click

web/.eslintrc

@@ -33,5 +33,6 @@
         "unnamedComponents": "arrow-function"
       }
     ]
-  }
+  },
+  "overrides": [{ "files": ["./public/sw.js"], "rules": { "no-restricted-globals": "off" } }]
 }