AmpereAltraPkg: Add FlashLib library instance

Provides functions to access the NVRAM, NVRAM2 and FailSafe region on the
Flash over MM communication.

Cc: Thang Nguyen <thang@os.amperecomputing.com>
Cc: Chuong Tran <chuong@os.amperecomputing.com>
Cc: Phong Vo <phong@os.amperecomputing.com>
Cc: Leif Lindholm <leif@nuviainc.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Nate DeSimone <nathaniel.l.desimone@intel.com>

Signed-off-by: Nhi Pham <nhi@os.amperecomputing.com>
Reviewed-by: Leif Lindholm <leif@nuviainc.com>