Improve Windowing sample with new features #902

What would you like to be added? 💡

Add new sample pages to the Windowing sample:

• Illustrating Window.ExtendsContentIntoTitleBar API to allow extending XAML UI the titlebar area while preserving the caption buttons
• Illustrating the SetBorderAndTitleBar API with (true, false) to completely extend the client area and hide the caption buttons (allowing the user to render their own custom buttons - including InputNonClientPointerSource.SetRegionRects for Maximize button to support Snap layouts menu)
• Illustrating the usage of InputNonClientPointerSource.SetRegionRects for Caption (the sample could display a red rectangle in the middle of the window that would allow dragging the whole window)

Why is this needed? 🤔

No response

Renderer 🎨

• Skia
• Native

For which platforms 📱💻🖥️

No response

Anything else we need to know? 💬

No response