Currently, when having action that are not represented by it's own permission (such as
canceling a task requires `edit_task` as opposed to `cancel_task` permission) one needs
to define the mapping both when defining the permissions (`permission { 'api/tasks' => [:cancel] }`)
for checking the routes, and redefine the `action_permission` in the controller for `find_resource`
purposes.

It would be more convenient if the `action_permission` method would be able to load the needed
permission from the permission definition (overriding would still be possible if needed).