HeaderedControls (#109)

* Init

* Remove other files

* Adding TreeView sample

* XAML styler

* Adding TreeView icon

* XAML styler

* Some more XAML styling

* Addressing feedback

* XAML styler

* xaml styler

* Fix for mismatch in WUX/MUXC TreeViewItem type in Sample

Caused unhelpful exception when running in UWP

* Fix test, sample

* Include Controls in PackageId

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Co-authored-by: michael-hawker <24302614+michael-hawker@users.noreply.github.com>
Co-authored-by: Arlo Godfrey <arlo.godfrey@outlook.com>

Author: 3 people