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/CMakeLists.txt

@@ -0,0 +1,20 @@
+cmake_minimum_required(VERSION 3.13)
+
+project(nlohmann_json)
+
+add_library(nlohmann_json INTERFACE)
+
+target_include_directories(nlohmann_json INTERFACE
+    ${CMAKE_CURRENT_SOURCE_DIR}
+)
+
+target_sources(nlohmann_json INTERFACE
+    ${CMAKE_CURRENT_SOURCE_DIR}/json.hpp
+    ${CMAKE_CURRENT_SOURCE_DIR}/json_fwd.hpp
+    ${CMAKE_CURRENT_SOURCE_DIR}/adl_serializer.hpp
+    ${CMAKE_CURRENT_SOURCE_DIR}/byte_container_with_subtype.hpp
+    ${CMAKE_CURRENT_SOURCE_DIR}/ordered_map.hpp
+)
+
+# Require C++11 for nlohmann/json
+target_compile_features(nlohmann_json INTERFACE cxx_std_11)