MM-55468 Ensure custom status emojis exist (#25501)

* MM-55468 Ensure custom status emojis exist

* Fix plugin API unit test

* Print underlying error as detailed error message

* Convert CustomStatusModal tests to React Testing Library and improve a11y

* Don't suggest custom statuses with non-existent emojis

* Silence test error by providing fake translation strings

server/i18n/en.json

@@ -1717,6 +1717,10 @@
     "id": "api.custom_status.recent_custom_statuses.delete.app_error",
     "translation": "Failed to delete the recent status. Please try adding the status first or contact your system administrator for details."
   },
+  {
+    "id": "api.custom_status.set_custom_statuses.emoji_not_found",
+    "translation": "Failed to update the custom status. An emoji with the given name does not exist."
+  },
   {
     "id": "api.custom_status.set_custom_statuses.update.app_error",
     "translation": "Failed to update the custom status. Please add either emoji or custom text status or both."