installer: add UI

build/VStudio/installer/winfsp_msi.wixproj

@@ -32,6 +32,12 @@
   <ItemGroup>
     <Compile Include="Product.wxs" />
   </ItemGroup>
+  <ItemGroup>
+    <WixExtension Include="WixUIExtension">
+      <HintPath>$(WixExtDir)\WixUIExtension.dll</HintPath>
+      <Name>WixUIExtension</Name>
+    </WixExtension>
+  </ItemGroup>
   <Import Project="$(WixTargetsPath)" />
   <!--
 	To modify your build process, add your task inside one of the targets below and uncomment it.