MdeModulePkg: SmmLockBoxSmmLib: Support StandaloneMm for SmmLockBoxLib

MdeModulePkg: SmmLockBoxSmmLib: Support StandaloneMm for SmmLockBoxLib

This change added support of StandaloneMm for SmmLockBoxLib. It replaces
gSmst with gMmst to support both traditional MM and standalone MM. The
contructor and desctructor functions are abstracted to support different
function prototype definitions.

Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Hao A Wu <hao.a.wu@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Signed-off-by: Kun Qin <kun.q@outlook.com>
Reviewed-by: Hao A Wu <hao.a.wu@intel.com>