feat: Add new assertm macro

This allows to add a message to the assertion which can improve
readability of error diagnostics.

fairmq/Error.h

@@ -9,10 +9,15 @@
 #ifndef FAIR_MQ_ERROR_H
 #define FAIR_MQ_ERROR_H
 
+#include <cassert>
 #include <fairmq/tools/Strings.h>
 #include <stdexcept>
 #include <system_error>
 
+// Macro copied from https://en.cppreference.com/w/cpp/error/assert
+// Use (void) to silent unused warnings.
+#define assertm(exp, msg) assert(((void)msg, exp))
+
 namespace fair::mq {
 
 struct RuntimeError : ::std::runtime_error