Migrate validation to Pester (#1249)

* remove Validate-* scripts

* Remove references to validation scripts from .json files

* Separate "It"s by new lines

* Remove new line before the first  "It"

* Separate "It"s by new lines

* remove 32-bit WinAppDriver check

* remove explicit variable definition

Co-authored-by: Sergey Dolin <v-sedoli@micorosoft.com>

images/win/scripts/Tests/WDK.Tests.ps1

@@ -0,0 +1,11 @@
+Describe "WDK" {
+    It "WDK exists" {
+      $WDKVersion = (Get-CimInstance -ClassName Win32_Product -Filter "Name = 'Windows Driver Kit'").Version
+      $WDKVersion| Should -Not -BeNullOrEmpty
+    }
+
+    It "WDK version from system" {
+      $version = Get-VSExtensionVersion -packageName "Microsoft.Windows.DriverKit"
+      $version | Should -Not -BeNullOrEmpty
+    }
+}