.NET10 Migration (#946)

Runtime and build
- Move all projects to .NET 10 with SDK-style project files and a shared
  Directory.Build.props (WIN/LINUX, x86/x64 defines)
- Load managed and unmanaged dependencies from libs/managed and
  libs/unmanaged through assembly and native library resolvers
- Compile party modes with Roslyn instead of CodeDom
- Update AppVeyor to the .NET 10 SDK and dotnet test
- Download the FFmpeg and gstreamer runtimes from the dependencies
  repository during the build
- Remove the VC++ 2015-2022 runtime check, no dependency needs it anymore

Graphics and windowing
- Replace the Direct3D 9 renderer with Direct3D 11 (Vortice)
- Pace Direct3D 11 frames with a frame latency waitable swap chain
- Move window, input and message boxes to SDL3
- Replace System.Drawing with SkiaSharp and WinForms with SDL3 and a
  software renderer

Video and audio
- Replace Acinerella with FFmpeg 8.1.3 (FFmpeg.AutoGen)
- Add hardware accelerated video decoding (D3D11VA, DXVA2, VideoToolbox,
  VAAPI, VDPAU) with software fallback
- Convert YUV video frames to RGB on the GPU in Direct3D 11 and OpenGL
- Add the video options HardwareDecoding, GpuColorConversion,
  DecoderThreads and VideoDownscaleResolution
- Update OpenAL to OpenTK 4 and NAudio recording to WasapiRecorder

Fixes
- Fix the song preview start and shorten the reporter buttons
- Fix a crash when opening the highscore without a selected song
- Use the options slide highlight in the party mode screens to avoid
  brightness flicker on VRR displays
- Disable GameInput in the x86 build, SDL3 crashes in GameInputCreate
  on 32-bit systems with the GameInput runtime installed
- Fix a truncation warning in PitchTracker

VocaluxeWeb/Hosting/CCertificateProvider.cs

@@ -37,7 +37,7 @@ namespace VocaluxeWeb.Hosting
             {
                 try
                 {
-                    var existing = new X509Certificate2(File.ReadAllBytes(path), (string)null, X509KeyStorageFlags.UserKeySet);
+                    var existing = X509CertificateLoader.LoadPkcs12(File.ReadAllBytes(path), null, X509KeyStorageFlags.UserKeySet);
                     if (existing.NotAfter > DateTime.Now.AddDays(7) && _Covers(existing, hostName, addresses))
                     {
                         return existing;
@@ -57,7 +57,7 @@ namespace VocaluxeWeb.Hosting
             }
 
             File.WriteAllBytes(path, pfx);
-            return new X509Certificate2(pfx, (string)null, X509KeyStorageFlags.UserKeySet);
+            return X509CertificateLoader.LoadPkcs12(pfx, null, X509KeyStorageFlags.UserKeySet);
         }
 
         private static bool _Covers(X509Certificate2 cert, string hostName, IEnumerable<IPAddress> addresses)