Adjust acceptance tests to changes in link shares

Although now it is possible to create several link shares the acceptance
tests currently handles only the first link share; this first link share
is now created by clicking an "Add new share" button instead of a
checkbox.

Besides that, the "Copy link" button has been moved from the menu to the
row, next to the menu trigger.

Signed-off-by: Daniel Calviño Sánchez <danxuliu@gmail.com>