title: AvaloniaUI Datagrid focus back on editing control after error notification
body: <p>I have a simple datagridtextcolumn:</p>
  <pre><code>&lt;DataGridTextColumn
          Header=&quot;Departing Date&quot;
          Binding=&quot;{Binding DepartingDateString}&quot;
  /&gt;
  </code></pre>
  <p>My model implements INotifyDataErrorInfo</p>
  <p>I do get an error whenever the wrong data is input:
  <a href="https://i.stack.imgur.com/bq1mB.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/bq1mB.png" alt="enter image description here" /></a></p>
  <p>However, the focus is lost and would require a mouse input to focus back unto the editing textbox. Is there a way to get it automatically focused back or at least using a keyboard key?</p>