[Kernel] Make XexUnloadImage fully release the image

Previously XexUnloadImage did not cleanup the image fully,
and if XexLoadImage was to be called again on the same module,
it was not initialized fully, leading to a crash when using it.

src/xenia/kernel/xboxkrnl/xboxkrnl_modules.cc

@@ -129,7 +129,8 @@ dword_result_t XexUnloadImage(lpvoid_t hmodule) {
     if (--ldr_data->load_count == 0) {
       // No more references, free it.
       module->Release();
-      kernel_state()->object_table()->RemoveHandle(module->handle());
+      kernel_state()->UnloadUserModule(object_ref<UserModule>(
+          reinterpret_cast<UserModule*>(module.release())));
     }
   }