Add UTF-8 path support (#1307)

Author: kennykerr

cppwinrt/app.manifest

@@ -3,6 +3,7 @@
 <application xmlns="urn:schemas-microsoft-com:asm.v3">
     <windowsSettings xmlns:ws2="http://schemas.microsoft.com/SMI/2016/WindowsSettings">
         <ws2:longPathAware>true</ws2:longPathAware>
+        <activeCodePage xmlns="http://schemas.microsoft.com/SMI/2019/WindowsSettings">UTF-8</activeCodePage>
     </windowsSettings>
 </application>
 </assembly>