set up react-native-xaml to support non-xaml objects

[jechternach]

Summary

It would be helpful to have support for non-xaml objects, such as composition objects that control animations

Motivation

Supports cases for applying animations to xaml objects, such as transition animations in gridView

Basic Example

<Style x:Key="sampleStyle" TargetType="GridView">
        <Setter Property="Template">
          <Setter.Value>
            <ControlTemplate TargetType="GridView">
              <GridView>
                <GridView.ItemContainerTransitions>
                  <TransitionCollection>
                        someAnimation
                  </TransitionCollection>
                </GridView.ItemContainerTransitions>
                <GridView.ItemsPanel>
                  <ItemsPanelTemplate>
                  </ItemsPanelTemplate>
                </GridView.ItemsPanel>
              </GridView>
            </ControlTemplate>
          </Setter.Value>
        </Setter>
</Style>

Open Questions

No response

[chrisglein]

Another deep layer to expose through JS, so this would be further out for any investment in react-native-xaml. Workaround for now is to define your animations in a XAML file and then have the JS refer back to that with a style key.