SecurityPkg:AuthVariableLib:Implement ECR1707 for Private Auth Variable

SecurityPkg:AuthVariableLib:Implement ECR1707 for Private Auth Variable

ECR1707 for UEFI2.7 clarified certificate management rule for private time-based
AuthVariable.Trusted cert rule changed from whole signer's certificate stack to
top-level issuer cert tbscertificate + SignerCert CN for better management compatibility.
Hash is used to reduce storage overhead.

Cc: Long Qin <qin.long@intel.com>
Cc: Chen Chen <chen.a.chen@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Chao Zhang <chao.b.zhang@intel.com>'
Reviewed-by: Long Qin <qin.long@intel.com>
Reviewed-by: Chen Chen <chen.a.chen@intel.com>