MdePkg/BaseLib: Add bit field population calculating methods

MdePkg/BaseLib: Add bit field population calculating methods

Hopefully this should tidy the conversion warnings.

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Add 32-bit and 64-bit functions that count number of set bits in a bitfield
using a divide-and-count method.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Tomas Pilar <tpilar@solarflare.com>
Cc: Liming Gao <liming.gao@intel.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>
Reviewed-by: Michael Kinney <michael.d.kinney@intel.com>