StandaloneMmPkg/FvLib: Add a common FV Library for management mode.

StandaloneMmPkg/FvLib: Add a common FV Library for management mode.

This patch implements a firmware volume library that can be used by the
Standalone management mode core module to parse the firmware volume.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Supreeth Venkatesh <supreeth.venkatesh@arm.com>
Reviewed-by: Achin Gupta <achin.gupta@arm.com>
Reviewed-by: Jiewen Yao <Jiewen.yao@intel.com>
Signed-off-by: Sughosh Ganu <sughosh.ganu@arm.com>