This class combines the configuration and the core rendering of the app-frame.
You can configure the content of the following sections
footer (only rendered if defined)
tabs (only rendered if defined)
In addition to that you can define how the sidebarToggle on small screens is rendered. By default is a hamburger-button.
The rendering function is used by the component factory functions appFrame, so it is not meant to be called directly unless you plan to implement your own appFrame.