Enforce unique Study names in a same Investigation

[rabuono]

To avoid confusion when navigating and searching, but also conflict in an ISAjson export, it would be good if DataHub would enforce unique Study names linked to a same Investigation.
Otherwise multiple different studies with the same title and filename (in the ISAjson file) might be referred to in a same Investigation.

[vdk88]

We might need to enable a study name uniqueness validator when DataHub features are switched on in the settings.

[rabuono]

Agreed. I assume that the rule of having unique study names inside one investigation (and not necessarily across investigations) will be enough.