Simplify User Settings and Group Settings to use existing Web nav instead of custom tabs

[lorenjohnson]

Due to recent elaborations in the HyloWebView component related to routing both inside and out of the WebView, we can now more readily use the existing navigation for each of the settings areas. The current ReactNavigation "MaterialTopTabs" use is an ok, but not great UX, and a minor bit of touch-ups for the responsive views of the settings areas will allow us to remove those and use the navigation between different settings areas already build in Web.

In addition to reducing the cost of App dev, a major benefit of this is that new settings area will automatically be available within the App.