title: Open file dialog with extension filter for a custom extension with kotlin
body: <p>Is there any way to set a file extension filter for this intent:
  I want to filter files with this extension ".xxx"</p>
  
  <pre><code>val intent = Intent()
                  .setType("*/*") // &lt;- it doesn't work if I put it here (".xxx")
                  .setAction(Intent.ACTION_GET_CONTENT)
              startActivityForResult(Intent.createChooser(intent, "Select a file (.xxx)"), OPEN_FILE_CODE)
  </code></pre>
  
  <p>Thank you!</p>