message_list: Don't always cache "Combined feed" view.

Important changes in this commit:
* We only cache message list for "Combined feed" if it is the
  default view.

* We modify existing handling of home message list code so that
  it can be used to for any message list that we want to cache
  using a new `preserve_rendered_state` variable.

* narrow_state.filter() returns the filter of combined feed view  list
  instead of `undefined`.

* We start fetching messages from the latest message on app load.

* Messages in all messages data and Recent view are always synced.

* If combined feed view list is not cached, we don't track it's
  last pointer, effectively sending user to the latest unread
  message always .

web/src/server_events_dispatch.js

@@ -175,7 +175,6 @@ export function dispatch_normal_event(event) {
 
         case "web_reload_client": {
             const reload_options = {
-                save_pointer: true,
                 save_compose: true,
                 message_html: "The application has been updated; reloading!",
             };