components: add SeparatedList

[slint]

The SeparatedList component util can be copied from
https://github.com/inveniosoftware/react-invenio-app-ils/blob/master/src/lib/components/SeparatedList/SeparatedList.js and used where we have delimiter-separated lists, like e.g. authors, aliases, acronyms, etc.

It would improve the readability in many of the cases, and avoid implementing the same joining logic all the time.

Originally posted by @kpsherva in #265 (comment)