Shell: Replace all dbg()'s with dbgln()

Author: https://github.com/alimpfard
Commit: 57728ef29f
Pull-request: https://github.com/SerenityOS/serenity/pull/4359
Issue: https://github.com/SerenityOS/serenity/issues/4345
Issue: https://github.com/SerenityOS/serenity/issues/4358

Shell/main.cpp

@@ -175,7 +175,7 @@ int main(int argc, char** argv)
     }
 
     if (command_to_run) {
-        dbgprintf("sh -c '%s'\n", command_to_run);
+        dbgln("sh -c '{}'\n", command_to_run);
         shell->run_command(command_to_run);
         return 0;
     }