Codechange: vendor the nlohmann-json library (#11290)

(cherry picked from commit ba67f39db6)

# Conflicts:
#	.github/workflows/ci-build.yml
#	CMakeLists.txt
#	COMPILING.md
#	src/os/macosx/survey_osx.cpp
#	src/os/windows/survey_win.cpp
#	src/script/api/script_admin.cpp
#	src/script/api/script_event_types.cpp
#	src/tests/test_script_admin.cpp

src/script/api/script_event_types.cpp

@@ -16,6 +16,7 @@
 #include "../../engine_base.h"
 #include "../../articulated_vehicles.h"
 #include "../../string_func.h"
+#include "../../3rdparty/nlohmann/json.hpp"
 #include "table/strings.h"
 
 #include "../../safeguards.h"