Add DRM Playback Support (PlayReady / Widevine) to WinUI 3 Media Pipeline

### Summary
WinUI 3 currently lacks support for protected media playback (DRM), including PlayReady and Widevine. This is a significant regression from UWP, which provided a complete DRM pipeline via MediaProtectionManager, PlayReady APIs, and Smooth Streaming/DASH support.

As a result, developers building modern media applications cannot migrate from UWP to WinUI 3, and must rely on browser-based solutions (WebView2 + EME) or native C++ Media Foundation pipelines. This blocks many real-world scenarios, including enterprise media apps, OTT streaming clients, and secure content delivery.
And it is one of reasons major companies did are shifting away from MAUI to WebApps as an example.

### Problem
- WinUI 3’s MediaPlayerElement does not support DRM.
- MediaProtectionManager cannot be used in WinUI 3 (no DRM pipeline behind it).
- PlayReady APIs exist in WinRT but are non-functional in Windows App SDK apps.
- There is no supported way to play encrypted DASH/Smooth Streaming content.
- WebView2 is not a suitable replacement for native playback in many scenarios, and the experience is bad.

### Impact
This limitation prevents:
- Migration of existing UWP media apps to WinUI 3.
- Development of new WinUI 3 apps requiring secure content playback.
- Adoption of Windows App SDK in media-heavy industries.
- Use of PlayReady, which is a core Windows DRM technology.

Major streaming apps (OTT, enterprise, education, medical, training) cannot adopt WinUI 3 without DRM support.

### Requested Feature
Add native DRM playback support to WinUI 3 / Windows App SDK, including:
- PlayReady SL3000 support
- Widevine (if possible)
- Integration with MediaPlayerElement
- Support for encrypted DASH and Smooth Streaming
- A replacement for MediaProtectionManager or equivalent API surface

### Why This Matters
UWP is not being in active development anymore, but it remains the only Windows app model that supports DRM playback. Without DRM support in WinUI 3, developers cannot migrate to the Windows App SDK, and Windows loses a key capability for modern media applications.

### Additional Notes
- PlayReady documentation still references UWP only.
- WebView2-based DRM is browser-dependent and not suitable for native media apps.
- Media Foundation DRM is not exposed to .NET developers without OEM licensing.

### Request
Please consider adding DRM playback support to WinUI 3 or provide guidance on the future of protected media on Windows for desktop applications aside WebView2.

Start by reviewing the MediaPlayerElement, MediaProtectionManager, and PlayReady API entry points described in the issue, along with the existing WinUI 3 and UWP DRM guidance. Done would require a supported native DRM path for PlayReady, possibly Widevine, encrypted DASH and Smooth Streaming, plus an equivalent protection API surface.

Written by the indexing model from the issue text.