HLE: CaptureManager: SaveScreenShot: properly handle screenshot image data

no way this was working before, and if it did, just pure luck, unsafe blind copy of bytes as is and zero checks.

i only tested tomodachi, but should fix all games that were crashing on saving screenshots

the crash was happening because the screenshot buffer was bigger than the bitmap buffer, so marshall.copy() was raising an unhandhled expection crashing the emu.

on top of this, because the data was just copied as is, the result image was garbled.

src/Ryujinx.HLE/HOS/Services/Caps/CaptureManager.cs

@@ -118,8 +118,11 @@ namespace Ryujinx.HLE.HOS.Services.Caps
                 }
 
                 // NOTE: The saved JPEG file doesn't have the limitation in the extra EXIF data.
-                using var bitmap = new SKBitmap(new SKImageInfo(1280, 720, SKColorType.Rgba8888));
-                Marshal.Copy(screenshotData, 0, bitmap.GetPixels(), screenshotData.Length);
+                using var bitmap = new SKBitmap(new SKImageInfo(1280, 720, SKColorType.Rgba8888, SKAlphaType.Premul));
+                int dataLen = screenshotData.Length > bitmap.ByteCount ? bitmap.ByteCount : screenshotData.Length;
+
+                Marshal.Copy(screenshotData, 0, bitmap.GetPixels(), dataLen);
+
                 using var data = bitmap.Encode(SKEncodedImageFormat.Jpeg, 80);
                 using var file = File.OpenWrite(filePath);
                 data.SaveTo(file);