SecurityPkg: Update DxeImageVerificationLib with following changes:

SecurityPkg: Update DxeImageVerificationLib with following changes:

1. Update to check image digest against dbx before execute it.
2. Update to support revoke certificate.
3. Update to support enroll unsigned PE image's Hash to allowed database (db). (Note: Unsigned Image's Hash is calculated in the same way with authenticode, the algorithm is assumed to be SHA256.)

Signed-off-by: xdu2
Reviewed-by: tye
Reviewed-by: gdong1
git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@12598 6f19259b-4bc3-4df7-8a09-765794883524