MdeModulePkg: StatusCodeHandler: StatusCodeHandler driver in StandaloneMm

MdeModulePkg: StatusCodeHandler: StatusCodeHandler driver in StandaloneMm

This change added support of StandaloneMm for StatusCodeHandler. It
adds a new instance of StatusCodeHandler of MM_STANDALONE type, and
abstracts the driver entrypoint into separate files, replaced gSmst with
gMmst, and switched to MM version of RscHandlerProtocol.

Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Hao A Wu <hao.a.wu@intel.com>
Cc: Dandan Bi <dandan.bi@intel.com>
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Signed-off-by: Kun Qin <kun.q@outlook.com>
Reviewed-by: Hao A Wu <hao.a.wu@intel.com>