BUILD: Refactor libpng submodule (#10238)

* relocate libpng files

* fix cmake build

* fix MSVC build

3rdparty/libpng/CMakeLists.txt

@@ -0,0 +1,22 @@
+# libPNG
+# Select the version of libpng to use, default is builtin
+if (NOT USE_SYSTEM_LIBPNG)
+	# We use libpng's static library and don't need to build the shared library and run the tests
+	set(PNG_SHARED OFF CACHE BOOL "Build shared lib" FORCE)
+	set(PNG_TESTS OFF CACHE BOOL "Build libpng tests" FORCE)
+	set(PNG_BUILD_ZLIB ON CACHE BOOL "ZLIB is already build or package is found" FORCE)
+	set(SKIP_INSTALL_ALL ON)
+	add_subdirectory(libpng EXCLUDE_FROM_ALL)
+	target_include_directories(png_static INTERFACE "${libpng_BINARY_DIR}" "${libpng_SOURCE_DIR}")
+
+	set(LIBPNG_TARGET png_static PARENT_SCOPE)	
+else()
+	find_package(PNG REQUIRED)
+
+	add_library(3rdparty_system_libpng INTERFACE)
+	target_include_directories(3rdparty_system_libpng INTERFACE ${PNG_INCLUDE_DIR})
+	target_link_libraries(3rdparty_system_libpng INTERFACE ${PNG_LIBRARY})
+	target_compile_definitions(3rdparty_system_libpng INTERFACE ${PNG_DEFINITIONS})
+
+	set(LIBPNG_TARGET 3rdparty_system_libpng PARENT_SCOPE)
+endif()