Add option to suppress feedback messages

This is used to dynamically exclude some test results from being shown to users, but still allows them to run in the background (e.g., for research).

config/locales/de.yml

@@ -75,6 +75,7 @@ de:
         file_type: Dateityp
         file_type_id: Dateityp
         hidden: Versteckt
+        hidden_feedback: Feedback ausblenden
         name: Name
         path: Pfad
         read_only: Schreibgeschützt

config/locales/en.yml

@@ -75,6 +75,7 @@ en:
         file_type: File Type
         file_type_id: File Type
         hidden: Hidden
+        hidden_feedback: Suppress feedback
         name: Name
         path: Path
         read_only: Read-only