Fix browser notification permission request logic (#13543)

* Add notification permission handling code

* Request notification permission when enabling any notification setting

* Add badge to notification settings when permissions insufficient

* Disable alerts by default, requesting permission and enable them on onboarding

app/javascript/mastodon/features/ui/components/notifications_counter_icon.js

@@ -3,6 +3,7 @@ import IconWithBadge from 'mastodon/components/icon_with_badge';
 
 const mapStateToProps = state => ({
   count: state.getIn(['notifications', 'unread']),
+  issueBadge: state.getIn(['settings', 'notifications', 'alerts']).includes(true) && state.getIn(['notifications', 'browserSupport']) && state.getIn(['notifications', 'browserPermission']) !== 'granted',
   id: 'bell',
 });