notifications: design and configuration updates

[kabeaty]

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What does this PR do?

These changes make some design and configuration updates to notifications.

These changes will impact:

• [x] commenters
• [ ] moderators
• [x] admins
• [ ] developers

What changes to the GraphQL/Database Schema does this PR introduce?

Adds the floatingBellIndicator to inPageNotifications settings.

Does this PR introduce any new environment variables or feature flags?

no

If any indexes were added, were they added to INDEXES.md?

n/a

How do I test this PR?

You can test these changes by:

1. Hover over the sticky corner bell on desktop. See a pointer cursor. Click the bell. Hover over close/bell icon in upper right. See a pointer cursor here too.
2. View comments in mobile to see the mobile toolbar. See that there is no longer an X option and the rest of the buttons have more space now because of that.
3. Load comment stream. Go to another tab/window. Go back. See the Refresh comments button. See that it has more padding now.
4. Go to admin configuration --> General --> In-page notifications. See the new Floating bell indicator option. See that when the overall in-page notifications is disabled, these options are disabled. See that when the in-page notifications are overall enabled, this floating bell indicator option is selectable. Enable it and go to the comment stream. See the notifications tab to the right and the floating bell button in the upper right. Disable it and go to the comment stream. See the notifications tab to the left and no floating bell button in the upper right when scrolling down the comment stream.

Were any tests migrated to React Testing Library?

How do we deploy this PR?