CMakeLists.txt: requires C++23 standard

CMakeLists.txt: add compiler version checks
adc_netserver.h: add AdcTrivialLogger class (use of 'deduced this'
feature of C++23 standard); AdcGenericNetServer class now has basic
based on std::basic_ostream logging capability

net/adc_net_concepts.h

@@ -160,8 +160,11 @@ concept adc_netservice_c = requires(SRVT srv, const SRVT srv_const) {
 
     srv.close();
 
-    // static method
-    SRVT::formatError(std::declval<typename SRVT::async_callback_err_t>(), std::declval<std::string&>());
+    // // static method
+    // SRVT::formatError(std::declval<typename SRVT::async_callback_err_t>(), std::declval<std::string&>());
+
+    // convert given error to formattable (valid input to std::format) representation
+    { SRVT::formattableError(std::declval<typename SRVT::async_callback_err_t>()) } -> traits::formattable;
 };