MdeModulePkg/Include: Add IpmiCommandLib header file

MdeModulePkg/Include: Add IpmiCommandLib header file

Add IpmiCommandLib to MdeModulePkg. This header file is
copied from edk2-platforms/Features/Intel/OutOfBandManagement/
IpmiFeaturePkg\Include\Library. Having this header file in
edk2 to avoid the dependence of edk2 module with edk2-platfrom.
The NULL instance of IpmiCommandLib under MdeModulePkg has
to be implemented for the same reason.
IpmiCommandLib.h in edk2-platforms should be removed once
this patch set is merged. Expect no impacts on edk2-platforms
because MdeModulePkg is referred in INF file by all edk2
modules under edk2-platforms that use IpmiCommandLib.

Signed-off-by: Abner Chang <abner.chang@amd.com>
Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Cc: Nickle Wang <nicklew@nvidia.com>
Cc: Igor Kulchytskyy <igork@ami.com>
Cc: Isaac Oram <isaac.w.oram@intel.com>
Cc: Nate DeSimone <nathaniel.l.desimone@intel.com>
Reviewed-by: Isaac Oram <isaac.w.oram@intel.com>
Reviewed-by: Igor Kulchytskyy <igork@ami.com>
Reviewed-by: Liming Gao <gaoliming@byosoft.com.cn>