MdePkg/UefiLib: Add EfiLocateProtocolBuffer()

https://bugzilla.tianocore.org/show_bug.cgi?id=838

Add new API to the UefiLib that locates and returns
an array of protocols instances that match a given
protocol.

Cc: Sean Brogan <sean.brogan@microsoft.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Michael D Kinney <michael.d.kinney@intel.com>
Reviewed-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Bret Barkelew <Bret.Barkelew@microsoft.com>