Add cimfs differ and snapshotter

Details about CimFs project are discussed in #8346

Signed-off-by: Amit Barve <ambarve@microsoft.com>

vendor/github.com/Microsoft/hcsshim/internal/safefile/safeopen.go

@@ -243,7 +243,7 @@ func RemoveRelative(path string, root *os.File) error {
 	if err == nil {
 		defer f.Close()
 		err = deleteOnClose(f)
-		if err == syscall.ERROR_ACCESS_DENIED {
+		if err == syscall.ERROR_ACCESS_DENIED { //nolint:errorlint
 			// Maybe the file is marked readonly. Clear the bit and retry.
 			_ = clearReadOnly(f)
 			err = deleteOnClose(f)