Bug 25606: Remove all reserve items button

Bug 25606: Remove all reserve items button

Adds button to course records to remove all attached reserve items. A warning dialog box will appear before executed.

Test plan
1. Install patch
2. Log in as user with permission to delete reserves
3. View a course reserve record with multiple items attached
4. There should now be a button that says "- Batch remove reserves"
5. When you click the button a dialog box should appear with a warning
6. Click "Ok"
7. All course reserves should be removed from the record
8. Add an item to more than course record
9. Redo 3-7
10. Items should have been removed from that course but remain on all other courses
11. Log in as a user without delete reserves permission
12. You should not see the batch remove option

Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>