Fix EZP-21955: Access to restricted content results in error 500

JIRA: https://jira.ez.no/browse/EZP-21955

This makes sure to throw a AccessDeniedException (and resulting HTTP 403: Access Denied)
if an UnauthorizedException is thrown in the repository service.

This is purposely left out of handleViewException as it should be a special/separate case of content exception.

Testing: Manual