Support every JSON Schema format for Draft 4

[jviotti]

These are the ones that are missing right now:

jsontoolkit/test/jsonschema/officialsuite.cc

Lines 191 to 192 in 46846a4

	// TODO: Enable all tests
	{"date-time", "email", "hostname", "ipv6"});

, which should be implemented here:

jsontoolkit/src/jsonschema/default_compiler_draft4.h

Lines 360 to 398 in 46846a4

	auto compiler_draft4_validation_format(const SchemaCompilerContext &context)
	-> SchemaCompilerTemplate {
	if (!context.value.is_string()) {
	return {};
	}
	// Regular expressions
	static const std::string FORMAT_REGEX_IPV4{
	"^(25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9][0-9]|[0-9])\\.(25[0-5]|2[0-4][0-"
	"9]|1[0-9][0-9]|[1-9][0-9]|[0-9])\\.(25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-"
	"9][0-9]|[0-9])\\.(25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9][0-9]|[0-9])$"};
	const auto &format{context.value.to_string()};
	if (format == "uri") {
	return {make<SchemaCompilerAssertionStringType>(
	context, SchemaCompilerValueStringType::URI,
	type_condition(context, JSON::Type::String),
	SchemaCompilerTargetType::Instance)};
	}
	#define COMPILE_FORMAT_REGEX(name, regular_expression) \
	if (format == (name)) { \
	return {make<SchemaCompilerAssertionRegex>( \
	context, \
	SchemaCompilerValueRegex{ \
	std::regex{(regular_expression), std::regex::ECMAScript}, \
	(regular_expression)}, \
	type_condition(context, JSON::Type::String), \
	SchemaCompilerTargetType::Instance)}; \
	}
	COMPILE_FORMAT_REGEX("ipv4", FORMAT_REGEX_IPV4)
	#undef COMPILE_FORMAT_REGEX
	return {};
	}

.

Some of them are somewhat URI related, like hostname and ipv6, which might need to first be implemented in URI Kit, which has #710 as a requirement. For example, for ipv6 we likely want a full blown IPv6 parser in place?