FmpDevicePkg: Add FmpDependencyDevice library class and NULL instance

FmpDevicePkg: Add FmpDependencyDevice library class and NULL instance

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=2696

This library provides firmware device specific services to support
saving dependency to firmware device and getting dependency from
firmware device.

Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Cc: Sean Brogan <sean.brogan@microsoft.com>
Signed-off-by: Wei6 Xu <wei6.xu@intel.com>
Reviewed-by: Sean Brogan <sean.brogan@microsoft.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>