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

@@ -7944,5 +7944,11 @@
   },
  "deleteProviderWarning": {
     "message": "Deleting your provider is permanent. It cannot be undone."
+  },
+  "errorAssigningTargetCollection": {
+    "message": "Error assigning target collection."
+  },
+  "errorAssigningTargetFolder": {
+    "message": "Error assigning target folder."
   }
 }