MdeModulePkg: Make HII configuration settings available to OS runtime

MdeModulePkg: Make HII configuration settings available to OS runtime

This feature is aimed to allow OS make use of the HII database
during runtime. In this case, the contents of the HII Database
is exported to a buffer. The pointer to the buffer is placed
in the EFI System Configuration Table, where it can be retrieved
by an OS application.

Cc: Liming Gao <liming.gao@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Brian J. Johnson <bjohnson@sgi.com>
Cc: Andrew Fish <afish@apple.com>
Cc: El-Haj-Mahmoud Samer <samer.el-haj-mahmoud@hpe.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Dandan Bi <dandan.bi@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>
Reviewed-by: Eric Dong <eric.dong@intel.com>