Add method to indicate completeness.

app/Import/Prerequisites/PrerequisitesInterface.php

@@ -53,6 +53,13 @@ interface PrerequisitesInterface
      */
     public function hasPrerequisites(): bool;
 
+    /**
+     * Indicate if all prerequisites have been met.
+     *
+     * @return bool
+     */
+    public function isComplete(): bool;
+
     /**
      * Set the user for this Prerequisites-routine. Class is expected to implement and save this.
      *