title: Bottom Navigation with center button arc or hump
body: <p>Looking to modify the Bottom Navigation Bar with a main center action button which changes the shape of the navigation bar itself either an arc like so
  <a href="https://i.stack.imgur.com/50aKq.png" rel="noreferrer"><img src="https://i.stack.imgur.com/50aKq.png" alt="enter image description here"></a></p>
  
  <p>or a hump in the bottom nav enveloping the center button around it. </p>
  
  <p>I'm fine if I have to extend the <code>BottomNavigationView</code> but I don't know where to start.</p>
  
  <p>I found <a href="https://stackoverflow.com/questions/50145541/new-bottom-layout-from-google">this similar question</a>, but it's not the exact problem I'm trying to solve.</p>