Nt32Pkg: Add Secure Boot build option including Custom Mode setup

If –D SECURE_BOOT_ENABLE is specified with the build command, Secure Boot support is enabled including custom mode setup.
This allows Secure Boot to be configured through setup allowing Nt32Pkg to be a fully functional Secure Boot reference platforms.

Signed-off-by:  <lee.g.rosenbaum@intel.com>
Reviewed-by:  <jiewen.yao@intel.com>

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@13186 6f19259b-4bc3-4df7-8a09-765794883524