Close autoupdate connections when tab is not active

[bastianjoel]

While a browser context is not visible to the user it should discontinue certain operations such as list sorting for example. For that a new service and helpers should be added which provide some apis for the browser context visibility status. For example a rxjs helper which blocks while a window is not visible and returns the last value when a window comes back in view.

As a first step autoupdate connections should be paused after a certain duration of inactivity.