Update sample app to use Windows SDK 10.0.2XXX and fix header missing issue

Author: Eve Le

SampleApps/WebView2SampleWinComp/CompositionHost.cpp

@@ -4,6 +4,7 @@
 
 #include "pch.h"
 
+#include <winrt/Windows.Foundation.Collections.h>
 #include "CheckFailure.h"
 #include "CompositionHost.h"
 #include <d2d1_1.h>

SampleApps/WebView2SampleWinComp/WebView2SampleWinComp.vcxproj

@@ -23,7 +23,7 @@
     <Keyword>Win32Proj</Keyword>
     <ProjectGuid>{abac8d87-c87b-455c-8340-0a9b0cd9a206}</ProjectGuid>
     <RootNamespace>WebView2SampleWinComp</RootNamespace>
-    <WindowsTargetPlatformVersion>10.0.18362.0</WindowsTargetPlatformVersion>
+    <WindowsTargetPlatformVersion>10.0.20348.0</WindowsTargetPlatformVersion>
   </PropertyGroup>
   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.Default.props" />
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'" Label="Configuration">