Always synchronise saved searches and dashboards in the UI, in case they are being updated by others at the same time.

## Description

When multiple users are interacting with the same saved search or dashboard at the same time, they override the changes of others, once they save their changes. We should make sure we always display the current version of the saved search or dashboard for all users. We should implement this it is transparent for all users, which changes have been made by others, while interacting with a saved search or dashboard.

Here is description of the relevant case:

1. User A creates a saved search and shares it with User B
2. User B is opening the saved search
3. User A is changing e.g. the search query and saving the changes
4. User B is e.g. changing the search query and saving the changes, without reloading the page since step 2

Step 4 will override the changes User A has made in step 3.

Related to https://github.com/Graylog2/graylog2-server/issues/12805

## Your Environment

* Graylog Version: 4.3