[Feature] Provide a Type MarkupExtension

[michael-hawker]

Describe the problem this feature would solve

To workaround this issue microsoft/microsoft-ui-xaml#4161, we may want to provide a simple Type provider Markup Extension in the Toolkit for 7.0 as a stop-gap until we understand more.

This would help with the SwitchPresenter and GraphPresenter in 7.0.

@Arlodotexe would you be up for adding yours which you've tested?