Add a way to execute a finally (try/finally) or catch (try/catch) step when error occurs and configuration is startNextLoop

@pmouawad ([Bug 61813](https://bz.apache.org/bugzilla//show_bug.cgi?id=61813&redirect=false)):
When load testing, I frequently have the following use case when analyzing a problem or for some particular applications that require explicit logout :

- Thread Group is set to restart next loop on error
- But I'd like to execute the equivalent of a finally block or goto

OS: All