Fix not found exceptions

[baumannsven]

• \ContaoCommunityAlliance\DcGeneral\Contao\View\Contao2BackendView\ActionHandler\DeleteHandler
• \ContaoCommunityAlliance\DcGeneral\View\ActionHandler\AbstractHandler
• \ContaoCommunityAlliance\DcGeneral\View\ActionHandler\ActionGuardTrait
• \ContaoCommunityAlliance\DcGeneral\Exception\NotCreatableException

[zonky2]

@baumannsven ist this issue related with MetaModels/contao-frontend-editing#13 (comment) and fix the the missing 401 forwarding? see Checkboxes