Bug 22898: Add selenium tests placing holds (staff)

Bug 22898: Add selenium tests placing holds (staff)

Quick selenium tests to prevent regressions like bug 22895.

Test plan:
Make sure the selenium tests return green

You can also test the buggy branch:
% git checkout v18.11.05
% prove t/db_dependent/selenium/basic_workflow.t
=> Failure
% git bz apply 22895.
% prove t/db_dependent/selenium/basic_workflow.t
=> Success

Signed-off-by: Victor Grousset <victor.grousset@biblibre.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>