Allow having the UrlNavigators below the tab bar
Some of the VDG and some users prefer having the UrlNavigators below the tab bar or are used to fill their toolbar to the brim. This commit restores these possibilities. The UrlNavigators will automatically be moved below the tab bar whenever the UrlNavigators are removed from the toolbar.
It is also now again possible to have the toolbar on the side. This option is disabled while the toolbar contains the UrlNavigators.
Overall this commit makes sure that upgrading users won't be affected by the new defaults.
This MR targets 20.12.
On a personal note I want to add that this MR was created despite the hysteria and hostility that some people showed and not because of it.