Make UrlNavigators in the toolbar the only option

Make UrlNavigators in the toolbar the only option

The UrlNavigators will be automatically added to the toolbar. The Sort By
action is removed from the default toolbar to make space.

Remove all options to have UrlNavigators outside the toolbar and remove
those code paths.

Make it so the new NavigatorsWidgetAction contains two UrlNavigators when
in split view mode. Spacing was also added to align these UrlNavigators
with the ViewContainers when enough space is available.

Force the toolbar to be either at the top or bottom of the window.

Set a sane sizeHint for DolphinUrlNavigator. It would be better to do this
in KUrlNavigator in the future.

This commit also contains a changes which should be moved to a separate
merge requests before this gets merged:
- Add an expansion animation when split view is enabled by the user