Resolve FTS-1961 "Se config"
This merge request fixes the bug described in FTS-1961:
When trying to configure a Storage Endpoint (SE) via the FTS REST interface https://:8446/config/se if the provided JSON object does not contain the
se_info
value or if these_info
value is an empty JSON an error is thrown on the server side.
It also adds extra testing to validate the different submission scenarios for SE configuration.