title: Center text of a Xamarin Forms TabbedPage Title
body: <p>i have a TabbedPage with multiple Child-Pages, with a title each. 
  When the title is short enough to be single line the text gets centered perfectly, but as soon as the text needs more than 1 line it is no longer centered.</p>
  
  <p>Can anyone tell me how to fix this?</p>
  
  <p><a href="https://i.stack.imgur.com/2zVRm.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/2zVRm.png" alt="enter image description here"></a></p>