Besides json_fwd.hpp, include analyzers also told clients of
<nlohmann/json.hpp> to include detail/json_ref.hpp (brace
initialization), json_literals.hpp (_json, _json_pointer),
adl_serializer.hpp, detail/macro_scope.hpp (NLOHMANN_DEFINE_*) and
detail/abi_macros.hpp. Mark those includes as exported, too.
ci_single_binaries only checked each header on its own, so it could not
notice this. It now also runs IWYU and clang-tidy's misc-include-cleaner
on small client programs in tests/iwyu_consumer, which fail on develop.
With the exports, json_literals.hpp no longer gets the json_fwd.hpp
suggestion that kept it out of the IWYU gate, so it is gated again.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
