Move any_authenticator, control_packet and pid_allocator to detail namespace

Summary: related to T13767

Reviewers: ivica

Reviewed By: ivica

Subscribers: miljen, iljazovic

Differential Revision: https://repo.mireo.local/D28084

test/include/test_common/packet_util.hpp

@@ -15,6 +15,8 @@
 
 namespace async_mqtt5::test {
 
+using control_code_e = async_mqtt5::detail::control_code_e;
+
 template <typename ...Strings>
 std::string concat_strings(Strings&&... strings) {
 	std::ostringstream stream;