Count failed checks and report when doing drush batch fixity check.

src/FixityCheckBatchCheck.php

@@ -219,6 +219,9 @@ class FixityCheckBatchCheck {
           if ($result->passed()) {
             $results['successful']++;
           }
+          else {
+            $results['failed']++;
+          }
         }
         else {
           // The check was not performed as the time elapsed since the last

src/FixityCheckServiceInterface.php

@@ -100,7 +100,7 @@ interface FixityCheckServiceInterface {
    *   elapsed since the last check has not exceed the required threshold.
    *
    * @return \Drupal\dgi_fixity\Entity\FixityCheckInterface|null
-   *   The resulting fixity_check if successful.
+   *   The resulting fixity_check if performed.
    *   NULL if the check was not performed because the time elapsed since the
    *   last check has not exceed the required threshold.
    */