message_list_data: Store message_list_data objects created locally.

[amanagr]

For #15131

@timabbott here is the list of events for which we will have to update the message_list_data objects we have stored locally:

• muted_topics
• muted_users
• stream update/create/delete events
• delete_message
• update_message events (stream/topic change)

Does the approach look good to you? I implemented what an update would look like for muted_topics.

[zulipbot]

Heads up @amanagr, we just merged some commits that conflict with the changes you made in this pull request! You can review this repository's recent commits to see where the conflicts occur. Please rebase your feature branch against the upstream/main branch and resolve your pull request's merge conflicts accordingly.

[amanagr]

Closing as I will open a new PR for this.