WiX: adjust the feature selection for the experimental ARM64 SDK

Add the option to permit control over the installation of the ARM64 bits
of the experimental SDK mirroring the other architectures.

Author: compnerd

platforms/Windows/platforms/windows/windows.wxs

@@ -3069,6 +3069,8 @@
 
     <?if $(IncludeARM64) = True?>
       <Feature Id="ExperimentalARM64" AllowAbsent="yes" Title="!(loc.Plt_ProductName_Windows_Experimental_arm64)">
+        <Level Condition="InstallARM64ExperimentalSDK = 1" Value="1" />
+
         <ComponentGroupRef Id="CoreFoundation.arm64" />
         <ComponentGroupRef Id="lib_Builtin_float.arm64" />
         <ComponentGroupRef Id="lib_Concurrency.arm64" />