title: Center text in angular snackbar
body: <p>what would be the correct way to center text in an angular snackbar?</p>
  
  <p>I've tried this, which doesn't work:</p>
  
  <pre><code>let config = new MatSnackBarConfig();
  config.panelClass = 'center';
  this.snackBar.open(message, undefined, config);
  </code></pre>
  
  <p>and then in some css file (either the same component, or in the global file):</p>
  
  <pre><code>.center {
     justify-content: center;
  }
  </code></pre>