StandaloneMmPkg/HobLib: Add HOB Library for management mode.

The Standalone MM environment is initialized during the SEC phase on ARM
Standard Platforms. The MM Core driver implements an entry point module
which is architecture specific and runs prior to the generic core driver
code. The former creates a Hob list that the latter consumes. This
happens in the same phase.

This patch implements a Hob library that can be used by the entry point
module to produce a Hob list and by the core driver code to consume it.

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