CMake: Update FindZLIB_NG For Target

Generate an import target to bring `FindZLIB_NG.cmake` up to
par with the CMake-default shipped `FindZLIB.cmake`.

cmake/FindZLIB_NG.cmake

@@ -27,9 +27,21 @@ else(ZLIB_NG_INCLUDE_DIR AND ZLIB_NG_LIBRARIES)
   set(ZLIB_NG_FOUND FALSE)
 endif(ZLIB_NG_INCLUDE_DIR AND ZLIB_NG_LIBRARIES)
 
+# generate CMake target
 if(ZLIB_NG_FOUND)
-  message(STATUS "Found zlib-ng: ${ZLIB_NG_LIBRARIES}, ${ZLIB_NG_INCLUDE_DIR}")
-endif(ZLIB_NG_FOUND)
+    message(STATUS "Found zlib-ng: ${ZLIB_NG_LIBRARIES}, ${ZLIB_NG_INCLUDE_DIR}")
+
+    set(ZLIB_NG_INCLUDE_DIRS ${ZLIB_NG_INCLUDE_DIR})
+
+    if(NOT TARGET ZLIB_NG::ZLIB_NG)
+      add_library(ZLIB_NG::ZLIB_NG UNKNOWN IMPORTED)
+      set_target_properties(ZLIB_NG::ZLIB_NG PROPERTIES
+          INTERFACE_INCLUDE_DIRECTORIES "${ZLIB_NG_INCLUDE_DIRS}")
+
+      set_property(TARGET ZLIB_NG::ZLIB_NG APPEND PROPERTY
+          IMPORTED_LOCATION "${ZLIB_NG_LIBRARIES}")
+    endif()
+endif()
 
 #[[
 Copyright https://github.com/zlib-ng/minizip-ng, 2021