Provide debug information about "Access Denied".

[kavics]

The "access denied" exception means the current user has not enough permission to execute an operation on a content-object. This is maybe a logical error. To discover it, the developer requires knowledge of the current user, object, and missing permissions. In most cases, writing the related information in the exception message is an information leak. So these exception messages need to be only "Access denied.". Because the access denial is not an error, its appearance in the event-log is not desirable.

Therefore the security-related exceptions need to write a Trace entry containing the message, user, content, and missing permission information.

UPDATE: we should simply write these additional trace messages where we raise these exceptions. There is no need to change the exceptions themselves.