ISTWCMS-7275: Rename "publication" to "reference" in custom block.

Updated class and form names, admin labels, and text strings to replace "publication" with "reference" for consistency and clarity in the custom block functionality. This aligns terminology with its intended purpose.

src/Service/UwBlockService.php

@@ -749,7 +749,7 @@ class UwBlockService {
       'opportunity' => $this->t('Opportunities'),
       'profile' => $this->t('Profiles'),
       'project' => $this->t('Projects'),
-      'publication_reference' => $this->t('Publication references'),
+      'publication_reference' => $this->t('References'),
       'service' => $this->t('Services'),
     ];
   }