Introduce the Windows lcow diff/snaphotter

Implements the Windows lcow differ/snapshotter responsible for managing
the creation and lifetime of lcow containers on Windows.

Signed-off-by: Justin Terry (VM) <juterry@microsoft.com>

services/diff/service_windows.go

@@ -19,5 +19,5 @@
 package diff
 
 var defaultDifferConfig = &config{
-	Order: []string{"windows"},
+	Order: []string{"windows", "windows-lcow"},
 }