TabBar should not take up space when hidden

[neilbalthaser]

In retool mobile apps it is possible to automatically hide the built-in tab bar at the bottom of the app by removing all content from the tab bar. But when the tab bar is hidden it still takes up space in the app container therefore there is a large gap between the bottom most component that is possible on a container and the actual bottom of the screen. It would be ideal to remove the actual space taken up by the tabBar when it is hidden.