MdeModulePkg: SmmSmiHandlerProfileLib: Support StandaloneMm Instance

MdeModulePkg: SmmSmiHandlerProfileLib: Support StandaloneMm Instance

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=3185

This change added support of SMI handler profile library router under
StandaloneMm. This change replaces gSmst with gMmst. It also abstracts
standalone and traditional MM driver entrypoints into separate files to
allow maximal common implementations.

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>
Cc: Ray Ni <ray.ni@intel.com>
Signed-off-by: Kun Qin <kun.q@outlook.com>
Reviewed-by: Hao A Wu <hao.a.wu@intel.com>