Because regex is built using a template string, \s* is actually escaped
into s*, i.e. literal "s" appearing 0 or more times. In most cases this
would mean that output can have spacing slightly off. In extreme case,
when identifier starts with letter "s", this could this could lead to
identifier being stored incorrectly.
Also adjusted tests to be more strict and mock data to cover this case.
Extended Mendeley Import test to include a scenario where other users
attached an annotation to an item in a group library that also exists
in user's library.
