Update indicator in hamburger icon (like persistent notifications)

[seanomat]

I appreciate all the work that is done to update notifications.
At the moment updates show in the configuration menu when available. Additionally there is a blue indicator in the sidebar.

This indicator might not be visible, since some users have the sidebar hidden, especially in the mobile apps.

It would be great, if this indicator would also show in the hamburger-icon similar to the indicator for persistent notifications.