Test control to play APNG files (Animated PNG) in WinUI 3 / C# with a SwapChainPanel
APNG format parsing mainly done with help from AI (Copilot here)
Most of APNG files in /Assets done with https://ezgif.com/gif-to-apng
(tested on Windows 10 22H2, Windows App SDK 1.7.250401001)
