[UCRT] Import Microsoft.Windows.SDK.CRTSource version 10.0.22621.3

Imported from https://www.nuget.org/packages/Microsoft.Windows.SDK.CRTSource/10.0.22621.3
License: MIT

sdk/lib/ucrt/string/wcsnset_s.cpp

@@ -0,0 +1,21 @@
+//
+// wcsnset_s.cpp
+//
+//      Copyright (c) Microsoft Corporation.  All rights reserved.
+//
+// Defines _wcsnset_s(), which sets at most the first 'count' characters of a
+// string to the given character and ensures that the resulting string is null-
+// terminated.
+//
+#include <corecrt_internal_string_templates.h>
+#include <string.h>
+
+extern "C" errno_t __cdecl _wcsnset_s(
+    wchar_t* const destination,
+    size_t   const size_in_elements,
+    wchar_t  const value,
+    size_t   const count
+    )
+{
+    return common_tcsnset_s(destination, size_in_elements, value, count);
+}