Notification icon to alert user when background services fail

[jmaassen]

Any issues with background services are shown in the background services tab, but there is no visual indication in the other tabs that something is wrong.

I ran into this when testing PR #1279. When disabling a package manager link as an admin (by setting the error message), there was no visual indication as a user in the package managers tab. It took me a few moments to realize that this is shown in the background services tab.

It maybe useful to add some notification icon to the relevant locations in the other tabs to alert the users of a problem. Clicking this icon could then take the user to the background services tab. This could be used for the package managers, but also for the repository link, etc.