[PM-7304] Add missing i18n keys for import errors (#8743)

* Add static error message when import fails

* Adding missing string on CLI for unassigned items

* Added missing string on setImportTarget

* fixed tests

apps/browser/src/_locales/en/messages.json

@@ -3011,5 +3011,11 @@
   },
   "unassignedItemsBannerSelfHost": {
     "message": "Notice: On May 2, 2024, unassigned organization items will no longer be visible in the All Vaults view and will only be accessible via the Admin Console. Assign these items to a collection from the Admin Console to make them visible."
+  },
+  "errorAssigningTargetCollection": {
+    "message": "Error assigning target collection."
+  },
+  "errorAssigningTargetFolder": {
+    "message": "Error assigning target folder."
   }
 }