title: Show modal bottom sheet with custom animation
body: <p>I was playing around with <code>showModalBottomSheet()</code> in Flutter and I was thinking about changing the default slide from bottom animation. Looking throught <a href="https://api.flutter.dev/flutter/material/BottomSheet-class.html" rel="nofollow noreferrer">flutter documentation</a> I saw that there is in fact a BottomSheet class that accept animation as parameters but, accordingly to the page, <code>showModalBottomSheet()</code> is preferrable.</p>
  
  <p>Is possible to control the animation in some way? I just need to change the default curve and duration.</p>
  
  <p>Thanks</p>