Setup Navigation Scaffolding

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There should be a bottom navigation bar. It should reflect the current view of the app. It should slide off the bottom of the screen when the bottom sheet opens.

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This is a bit difficult as CoordinatorLayout doesn't seem to have a good way of doing a thing with a bottom sheet and bottom navigation bar. Two ideas: MotionLayout or a custom behavior.

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I think MotionLayout will land in a month or two.