KabylakeOpenBoardPkg/GalagoPro3: Add build files

REF:https://bugzilla.tianocore.org/show_bug.cgi?id=2207



 * Adds files required to build the GalagoPro3 board to the board
   directory.
 * Updates KabylakeOpenBoardPkg/OpenBoardPkg.dec to reference
   the new GalagoPro3 board directory.

Cc: Chasel Chiu <chasel.chiu@intel.com>
Cc: Nate DeSimone <nathaniel.l.desimone@intel.com>
Cc: Ankit Sinha <ankit.sinha@intel.com>
Cc: Jeremy Soller <jeremy@system76.com>
Signed-off-by: Michael Kubacki <michael.a.kubacki@intel.com>
Reviewed-by: Chasel Chiu <chasel.chiu@intel.com>
Reviewed-by: Nate DeSimone <nathaniel.l.desimone@intel.com>
Reviewed-by: Ankit Sinha <ankit.sinha@intel.com>
Reviewed-by: Jeremy Soller <jeremy@system76.com>