Hash the full UTF-8 byte length in HashStrings (#1355)

HashStrings passed str.Length (a char count) as the byte count to
MD5.TransformBlock, so for any non-ASCII string only a truncated prefix
of the UTF-8 bytes was hashed. Capture the byte array and use its Length.

BepInEx.Core/Utility.cs

@@ -331,7 +331,10 @@ public static class Utility
         using var md5 = MD5.Create();
 
         foreach (var str in strings)
-            md5.TransformBlock(Encoding.UTF8.GetBytes(str), 0, str.Length, null, 0);
+        {
+            var bytes = Encoding.UTF8.GetBytes(str);
+            md5.TransformBlock(bytes, 0, bytes.Length, null, 0);
+        }
 
         md5.TransformFinalBlock(new byte[0], 0, 0);