- Added new API to allow console pages knew whether they are visible or
not.
- Use new IConsole API to schedule console updates only if console page
is visible (top level) in the console view. This prevents multiple
opened consoles in same console view run update tasks every second, even
if no one can see the updated console name.
- Don't update console label if the elapsed time format is set to "None"
- Update console elapsed time format for running processes if preference
changes
- Added tests

Fixes https://github.com/eclipse-platform/eclipse.platform/issues/2478