Alternative Title

[lubitchv]

For our transition from Nesstar we will need "Alternative Title" field to be repeatable. According to DDI 2.5 specifications "Alternative Title" is repeatable and we would like to have it also in Dataverse.
Changing "Alternative Title" field in citation.tsv and in solar schema to multiple will make that field repeatable in UI. However in this case DDI Exporter and OpenAire exporter will break. Json exporter does not break.
For this feature to work these exporters should be fixed (change to multiple) and corresponding test also will need to be fixed.