chore: switch to CMake build system instead of native Visual Studio project

CMake/custom_import_iconv.cmake

@@ -0,0 +1,9 @@
+if (WIN32)
+    # In Windows, we should not import Iconv.
+    # Send a notice to programmer.
+    message("Windows environment detected, skip finding Iconv!")
+else ()
+    # In non-Windows, we simply import Iconv from CMake preset.
+    # It will produce Iconv::Iconv target for including and linking.
+    find_package(Iconv REQUIRED)
+endif ()