Add ToSpan for MemoryWriteStream and simplify code with it

Source/Engine/Serialization/MemoryReadStream.cpp

@@ -1,6 +1,7 @@
 // Copyright (c) 2012-2024 Wojciech Figat. All rights reserved.
 
 #include "MemoryReadStream.h"
+#include "Engine/Platform/Platform.h"
 
 MemoryReadStream::MemoryReadStream()
     : _buffer(nullptr)
@@ -22,6 +23,14 @@ void MemoryReadStream::Init(const byte* bytes, uint32 length)
     _length = length;
 }
 
+void* MemoryReadStream::Move(uint32 bytes)
+{
+    ASSERT(GetLength() - GetPosition() >= bytes);
+    const auto result = (void*)_position;
+    _position += bytes;
+    return result;
+}
+
 void MemoryReadStream::Flush()
 {
 }