[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/desktop/src/locales/en/messages.json

@@ -2705,5 +2705,11 @@
   },
   "passkeyRemoved": {
     "message": "Passkey removed"
+  },
+  "errorAssigningTargetCollection": {
+    "message": "Error assigning target collection."
+  },
+  "errorAssigningTargetFolder": {
+    "message": "Error assigning target folder."
   }
 }