feat: export marks as csv or pdf (#427)

* worked on the marks csv export

* added translations

* added pdf export option and translations

* cleanup

* cleanup

* improve download UX

* capitalize title

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Co-authored-by: Rotimi Best <best@classroomio.com>

apps/dashboard/src/lib/utils/translations/de.json

@@ -475,7 +475,11 @@
         "title": "Markierungen",
         "student": "Student",
         "total": "Gesamt",
-        "no_student": "Kein Student hinzugefügt"
+        "no_student": "Kein Student hinzugefügt",
+        "export": {
+          "csv": "Als CSV exportieren",
+          "pdf": "Als PDF exportieren"
+        }
       },
       "submissions": {
         "title": "Eingereichte Übungen",