Add lookup for "Related works" dropdown

[ekate]

On the deposit form page there is a section "Related works". In that section there is a dropdown with the list of relation.
It's repeatable filed and javascript element used is -
<div aria-invalid="true" name="metadata.related_identifiers.<i>.relation_type" required="" id="metadata.related_identifiers.<i>.relation_type" role="listbox" aria-expanded="false" class="ui fluid selection dropdown" tabindex="0">
The dropdown can be populated from api/vocabularies/relationtypes endpoints
We want to add lookup here so the user don't have to go through the whole list