unittests: Fixes unit tests for Windows (part 10)

Currently, there are some unit tests that are failing on
Windows due to various reasons:

- Different "File not found" error messages on Windows.
- Files need to be closed on Windows before removing them.
- The default RootHnsEndpointName (root-hnsendpoint-name) flag value is 'cbr0'
- On Windows, Unix Domain sockets are not checked in the same way in golang, which is why
  hostutils_windows.go checks for it differently. GetFileType will return an error in this
  case. We need to check for it, and see if it's actually a Unix Domain Socket.

pkg/volume/util/hostutil/hostutil.go

@@ -41,6 +41,10 @@ const (
 	FileTypeUnknown FileType = ""
 )
 
+var (
+	errUnknownFileType = fmt.Errorf("only recognise file, directory, socket, block device and character device")
+)
+
 // HostUtils defines the set of methods for interacting with paths on a host.
 type HostUtils interface {
 	// DeviceOpened determines if the device (e.g. /dev/sdc) is in use elsewhere
@@ -108,5 +112,5 @@ func getFileType(pathname string) (FileType, error) {
 		return FileTypeBlockDev, nil
 	}
 
-	return pathType, fmt.Errorf("only recognise file, directory, socket, block device and character device")
+	return pathType, errUnknownFileType
 }