Add delay to server-error toast

[lardcanoe]

Based on changes from the discussion at https://elixirforum.com/t/delaying-liveview-js-commands-avoid-quick-flash-of-trying-to-reconnect/64035/9?u=sevensidedmarble

This adds a 3s delay before showing the server-error toast, giving the client a chance to reconnect before showing it.