Convert parse_delete_tokens_list() and unparse_share_modes() to use ndr encoding...

Convert parse_delete_tokens_list() and unparse_share_modes() to use ndr encoding for the struct security_unix_token. We can do this as libsmb_share_modes never looks inside the delete tokens list, only implicitly gets the length.
(cherry picked from commit 5b5351022fb81da09d28ab3e7c8c2e2a8956c45e)