Use and extend the detail helpers to remove duplicated code (#5783)

* Use and extend the detail helpers to remove duplicated code

Library:
- binary_reader: format bytes with hex_byte() instead of snprintf
- add throw_type_must_be() for the 20 copies of type_error.302
- binary_reader: add last_byte_error()/unexpected_byte() for the 32
  "parse error at the last read byte" sites (replaces bon8_error)
- json_sax: add check_container_size() for out_of_range.408 and
  diagnostic_positions::set_container_start/_end()
- json_pointer: add throw_no_parent() (405) and throw_unresolved() (404)

Tests:
- unit-class_parser uses the shared utils::SaxCountdown
- move SaxEventLogger (and its ExitAfter* variants) from unit-class_parser
  and unit-deserialization into the new tests/src/test_sax.hpp

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Factor out more repeated error paths and test boilerplate

Library:
- add throw_cannot_use_with() for the 34 copies of type_error.304-312
  "cannot use X with Y"
- iter_impl: add throw_cannot_get_value() (invalid_iterator.214)
- parser: add syntax_error() for the 12 parse_error.101 sites
- ordered_map: share the four at() bodies via at_impl()
- json_sax_dom_callback_parser: add pop_container() for end_object()
  and end_array()
- binary_reader: build the two UBJSON/BJData length-type messages with
  concat() and last_byte_error()

Tests:
- move same_value(), the NDEBUG guard, and step 0 (parse without
  exceptions) of the seven fuzzer drivers into tests/src/fuzzer_common.hpp

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Name the exception ids and address review comments

Add detail::exception_id, a scoped enum with one named enumerator per
documented exception id, and use it for every id in the library. The
create() functions get an overload for it; the int overloads stay for
user code.

Following the review of #5783: add binary_reader::invalid_byte() and
length_type_error(), basic_json::throw_subscript_wrong_type(), move the
fuzzer includes and the using-declaration into fuzzer_common.hpp, and
rename test_sax.hpp to sax_event_loggers.hpp.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Silence -Wweak-vtables for the SAX event loggers

The loggers moved from anonymous namespaces in the test files into
sax_event_loggers.hpp, so clang now warns that their vtables are
emitted in every translation unit.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Silence MSVC 2015 C4100 in parser::syntax_error for static SAX::parse_error

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Inline invalid_byte() into its call sites

The wrapper only fixed the message string of unexpected_byte(), which is
the same kind of per-argument helper that was declined for
throw_type_must_be(). Call unexpected_byte("invalid byte", ...) directly.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

include/nlohmann/detail/conversions/to_json.hpp

@@ -414,13 +414,13 @@ inline void to_json(BasicJsonType& j, const EnumKeyedMap& map)
         BasicJsonType key = p.first;
         if (JSON_HEDLEY_UNLIKELY(!key.is_string()))
         {
-            JSON_THROW(type_error::create(302, concat("type must be string, but is ", key.type_name()), &key));
+            throw_type_must_be("string", key);
         }
 
         auto& key_string = *key.template get_ptr<typename BasicJsonType::string_t*>();
         if (JSON_HEDLEY_UNLIKELY(!obj.emplace(key_string, BasicJsonType(p.second)).second))
         {
-            JSON_THROW(type_error::create(318, concat("duplicate object key '", key_string, "'"), &key));
+            JSON_THROW(type_error::create(exception_id::enum_key_duplicate, concat("duplicate object key '", key_string, "'"), &key));
         }
     }
     external_constructor<value_t::object>::construct(j, std::move(obj));