fix(windows): unable to override WindowsTargetVersion (#714)

* renaming the project name to DateTimePicker

* added import for ExperimentalFeatures.props file if exists in the root of the repo

Author: NikhiRaya

windows/DateTimePickerWindows/DateTimePickerWindows.vcxproj

@@ -1,5 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <Project DefaultTargets="Build" ToolsVersion="15.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <Import Project="$(SolutionDir)\ExperimentalFeatures.props" Condition="Exists('$(SolutionDir)\ExperimentalFeatures.props')" />
   <Import Project="$(SolutionDir)packages\Microsoft.Windows.CppWinRT.2.0.200316.3\build\native\Microsoft.Windows.CppWinRT.props" Condition="Exists('$(SolutionDir)packages\Microsoft.Windows.CppWinRT.2.0.200316.3\build\native\Microsoft.Windows.CppWinRT.props')" />
   <PropertyGroup Label="Globals">
     <CppWinRTOptimized>true</CppWinRTOptimized>