Bug 26322: Permissions not checked correctly for plugins

This patch fixes the logic in a condition to address the fact that
permissions are not checked for plugins. This was due to bad parenthesis
pairing and the lack of good tests for this.

To test:
1. Apply the regression tests patch
2. Run:
   $ kshell
  k$ prove t/db_dependent/Koha/REST/Plugin/PluginRoutes.t
=> FAIL: Tests fail because of bad logic
3. Apply this patch
4. Repeat (2)
=> SUCCESS: Tests pass!
5. Verify the tests cover the use cases that are needed:
   - Anonymous access
   - Real user with wrong permissions (parameters => 1)
   - Real user with right permissions (borrowers => 1)
=> SUCCESS: Needed use cases so we catch any regression are found
6. Sign off :-D

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Joonas Kylmälä <joonas.kylmala@helsinki.fi>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>

Koha/REST/V1/Auth.pm

@@ -255,7 +255,7 @@ sub authenticate_api_request {
     if ( !$authorization and
          ( $params->{is_public} and
           ( C4::Context->preference('RESTPublicAnonymousRequests') or
-            $user) ) or $params->{is_plugin} ) {
+            $user) or $params->{is_plugin} ) ) {
         # We do not need any authorization
         # Check the parameters
         validate_query_parameters( $c, $spec );