When a person has exhausted all administrative remedies available within an agency, and is aggrieved by a final decision or order in a contested case, whether such decision or order is affirmative or negative in form, the decision or order is subject to direct review by the courts as provided by law. Exhaustion of administrative remedies does not require the filing of a motion or application for rehearing or reconsideration unless the agency rules require the filing before judicial review is sought. A preliminary, procedural or intermediate agency action or ruling is not immediately reviewable, except that the court may grant leave for review of such action if review of the agency's final decision or order would not provide an adequate remedy.