title: How to filter a mat-tree component Angular Material 6.0.1
body: <p>I'm using mat-tree angular material component.
  It's a nice component with some very useful features like, multi-select, expand all/collapse all.
  I was not able to find any tree filtering feature in any of their APIs.
  Has anyone came across this feature or done any work around to get mat-tree filter?</p>
  
  <p><a href="https://i.stack.imgur.com/whwib.png" rel="noreferrer"><img src="https://i.stack.imgur.com/whwib.png" alt="enter image description here"></a></p>