MM-21336: Improve channel rename restrictions (#13441)

* MM-21336: Improve channel rename restrictions

Non-direct channels should not have __ in them.

* Fix order of i18n extraction

* Incorporate review comments

Use a more relaxed check by actually checking for valid userIds.

* Improve error message

i18n/en.json

@@ -371,6 +371,10 @@
     "id": "api.channel.update_channel.deleted.app_error",
     "translation": "The channel has been archived or deleted"
   },
+  {
+    "id": "api.channel.update_channel.invalid_character.app_error",
+    "translation": "Invalid channel name. User ids are not permitted in channel name for non-direct message channels."
+  },
   {
     "id": "api.channel.update_channel.tried.app_error",
     "translation": "Tried to perform an invalid update of the default channel {{.Channel}}"