CryptoPkg: Remove deprecated function usage in X509GetCommonName()

CryptoPkg: Remove deprecated function usage in X509GetCommonName()

BZ#: https://bugzilla.tianocore.org/show_bug.cgi?id=923

X509_NAME_get_text_by_NID() used in X509GetCommonName() implementation
is one legacy function which have various limitations. The returned
data may be not usable  when the target cert contains multicharacter
string type like a BMPString or a UTF8String.
This patch replaced the legacy function usage with more general
X509_NAME_get_index_by_NID() / X509_NAME_get_entry() APIs for X509
CommonName retrieving.

Tests: Validated the commonName retrieving with test certificates
       containing PrintableString or BMPString data.

Cc: Ye Ting <ting.ye@intel.com>
Cc: Michael Turner <Michael.Turner@microsoft.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Long Qin <qin.long@intel.com>
Reviewed-by: Ye Ting <ting.ye@intel.com>