Suggest alternative Queue driver when reaching certain metric cap

## Feature Request

**Is your feature request related to a problem? Please describe.**
When reaching a certain scale in users following discussions, the `sync` driver can cause xhr calls to time out.

**Describe the solution you'd like**

We should calculate the number of notifications sent each hour, using the related Model. Once the count reaches a specific threshold we will show a widget on the admin area suggesting to install a different queue driver.

The issue names the sync queue driver, notification counts from a related Model, and an admin-area widget, but no files or tests. Start by locating the notification model and queue-driver configuration, then determine the threshold and admin entry point; done means a defined metric triggers a clear driver recommendation.

Written by the indexing model from the issue text.