CryptoPkg: Add new API to retrieve commonName of X.509 certificate

CryptoPkg: Add new API to retrieve commonName of X.509 certificate

v3: Add extra CommonNameSize check since OpenSSL didn't check this
    input parameter. (One openssl issue was filed to address this risk:
    https://github.com/openssl/openssl/issues/4392)
v2: Update function interface to return RETURN_STATUS to represent
    different error cases.

Add one new API (X509GetCommonName()) to retrieve the subject commonName
string from one X.509 certificate.

Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Ting Ye <ting.ye@intel.com>
Cc: Chao Zhang <chao.b.zhang@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Qin Long <qin.long@intel.com>
Reviewed-by: Ye Ting <ting.ye@intel.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>