title: Blazor input select databind with nullable type and default value
body: <p>I have a <code>Guid?</code> bound to a <code>&lt;select&gt;</code>, and since this type is nullable, I want it to show the "All" option value when there is no value in the property. </p>
  
  <p>I tried this without success:</p>
  
  <pre><code>&lt;select @bind="MyLocalParameter"&gt;
      &lt;option value=""&gt;All&lt;/option&gt;
      @foreach (var item in Items)
      {
          &lt;option value="@item.IdGuid"&gt;@item.Name&lt;/option&gt;
      }
  &lt;/select&gt;
  </code></pre>
  
  <p>How can I do this?</p>