Bug 20568: API key management for OPAC users

Bug 20568: API key management for OPAC users

This patch makes the OPAC interface for API keys management work
with the new lib. Verify all actions work for a logged user.

Users without login should be redirected to an error page.

The AllowPatronsManageAPIKeysInOPAC syspref is added to control if the
OPAC feature is enabled or not.

To test:
- Verify the syspref works
- Verify users can manage their API keys

Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Julian Maurice <julian.maurice@biblibre.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>