title: Flutter SelectableText no Select All option on iOS
body: <p>I'm using <code>SelectableText.rich()</code> widget to allow user to copy the displayed text.
  On Android the default options in toolbar are Copy and Select All - I can also customize it.
  On iOS the default option appears to be only Copy and setting <code>ToolbarOptions</code> doesn't change that (only when I set copy to false, it disappears).
  My goal is to display Copy and Select All options on both Android and iOS.
  Am I missing something or is it some kind of a bug?</p>
  <pre><code>SelectableText.rich(
                            TextSpan(children: [
                              TextSpan(
                                text: &quot;Name\n&quot;,
                                style:
                                    TextStyles.getDetailViewLabelStyle(context),
                              ),
                              TextSpan(
                                text: projectName,
                                style:
                                    TextStyles.getDetailViewContentStyle(context),
                              )
                            ]),
                            toolbarOptions:
                                const ToolbarOptions(copy: true, selectAll: true),
                          ),
  </code></pre>