Provide an api to: retrieve all scripted field (names) in an instance#36

we are implementing a reporting on Jira, and would like to include also scripted fields. The maintainence of the tool will be far more robust if we do not “hardcode” the names of the scripted fields but allow the tool to “discover” the field names that are existing on this instance.

Once field names are know then the tool will add them to the integration