MdePkg/PeCoffGetEntryPointLib: Add PeCoffSerachImageBase()

MdePkg/PeCoffGetEntryPointLib: Add PeCoffSerachImageBase()

This new API only works on DEBUG build. It will search the PE/COFF image base
forward the input address in this PE/COFF image and returns it.

Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Michael Kinney <michael.d.kinney@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Jeff Fan <jeff.fan@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>