We introduce the script to audit the expiry date of X509 files
(i.e. crt/crl/csr files) in tests/data_files/ folder.
This commit add basic classes and the framework for auditing
and "-a" option to list all valid crt/crl/csr files it found.
Signed-off-by: Pengyu Lv <pengyu.lv@arm.com>
