Refactor folder (#10475)

Move many third-party components' source codes from the src folder to a new folder called deps_src. The goal is to make the code structure clearer and easier to navigate.

deps_src/nlohmann/detail/meta/void_t.hpp

@@ -0,0 +1,13 @@
+#pragma once
+
+namespace nlohmann
+{
+namespace detail
+{
+template<typename ...Ts> struct make_void
+{
+    using type = void;
+};
+template<typename ...Ts> using void_t = typename make_void<Ts...>::type;
+} // namespace detail
+}  // namespace nlohmann