Bug 25411: Regression tests

Bug 25411: Regression tests

This patch adds tests the new RESTPublicAnonymousRequests syspref
doesn't apply to routes added by plugins.

It is up to the plugin developer to handle those conditions.

To test:
1. Apply this patch
2. Run:
   $ kshell
  k$ prove t/db_dependent/Koha/REST/Plugin/PluginRoutes.t
=> FAIL: Notice the tests fail

Signed-off-by: Victor Grousset/tuxayo <victor@tuxayo.net>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>