Expand "Add a new section" feature when adding content to power BI App

[matt_uland]

When adding content to powerBI app, there is a feature that allows you to "Add a new section" to organize the content on the App. As of now, you can only do this at one layer (the top layer)--expand the functionality to be able to "Add a new section" at sub-levels, too so that content on an App can be organized with more layers of detail.