Add "Complete!" message after succesfull transaction

Keeping the last message something abou scriptlets is not clear
message that everything passed correctly and program was terminated
correctly. The commit uses the same message like DNF4. Contrary
to DNF4, this commit does not add Complete! message when there is
anything to perform - no transaction table.

Closes: #613

dnf5/main.cpp

@@ -1444,6 +1444,11 @@ int main(int argc, char * argv[]) try {
 
     log_router.info("DNF5 finished");
 
+    // Print Complete! message only when transaction is created to prevent poluting output from repoquery or other command
+    if (auto * transaction = context.get_transaction(); transaction && !transaction->empty()) {
+        std::cout << "Complete!\n";
+    }
+
     return static_cast<int>(libdnf5::cli::ExitCode::SUCCESS);
 } catch (const libdnf5::Error & e) {
     std::cerr << libdnf5::format(e, libdnf5::FormatDetailLevel::WithName);