We add Fmp->GetImage() support in CapsuleApp. So that user may call Fmp->GetImage() in UEFI shell environment. This is useful to do unit test for FMP which supports GetImage(), or user wants to get current image, such as Microcode. Cc: Eric Dong <eric.dong@intel.com> Cc: Jeff Fan <jeff.fan@intel.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Jiewen Yao <jiewen.yao@intel.com> Reviewed-by: Jeff Fan <jeff.fan@intel.com>