MdePkg: TimerRngLib: Added RngLib that uses TimerLib

Added a new RngLib that provides random numbers from the TimerLib
using the performance counter. This is meant to be used for OpenSSL
to replicate past behavior. This should not be used in production as
a real source of entropy.

Ref: https://github.com/tianocore/edk2/pull/845
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1871

Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Cc: Zhiguang Liu <zhiguang.liu@intel.com>
Reviewed-by: Liming Gao <gaoliming@byosoft.com.cn>
Signed-off-by: Matthew Carlson <matthewfcarlson@gmail.com>