EmulatorPkg/Win/Host: Fix image unload regression

EmulatorPkg/Win/Host: Fix image unload regression

https://bugzilla.tianocore.org/show_bug.cgi?id=2104

When UEFI Applications or UEFI Drivers are unloaded,
the PeCoffLoaderUnloadImageExtraAction() needs to unload
the image using FreeLibrary() if the image was successfully
loaded using LoadLibrrayEx().

This is a regression from the Nt32Pkg that supported
unloading applications and drivers as well as loading
the same application or driver multiple times.

Cc: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Ray Ni <ray.ni@intel.com>
Cc: Andrew Fish <afish@apple.com>
Tested-by: Tim Lewis <tim.lewis@insyde.com>
Signed-off-by: Michael D Kinney <michael.d.kinney@intel.com>