Set stream copy position to beginning

This is a manual port of #12953. The code was refactored in .NET 9 so the fix needs manually applied.

Author: JeremyKuhne

src/System.Drawing.Common/src/System/Drawing/Internal/GPStream.cs

@@ -20,6 +20,7 @@ internal GPStream(Stream stream, bool makeSeekable = true)
             // Copy to a memory stream so we can seek
             MemoryStream memoryStream = new MemoryStream();
             stream.CopyTo(memoryStream);
+            memoryStream.Position = 0;
             _dataStream = memoryStream;
         }
         else